contains advices for people who want to learn how networks work and the hardware that makes up the modern network architecture. Beginners will learn how to download the simulator software and how to start working with it.

The reader will find here the basics of configuring network devices. You will learn about network services such as TELNET, SSH, FTP, EMAIL, DHCP, DNS and routing protocols RIP, EIGRP, OSPF. Learn how to design and deploy VLANs. The authors, when describing the issues of administering computer networks, use many examples and exercises.

Proprietary names of companies, organizations, and products are used in the book solely to identify them.

Cover design: Daniel Pliszka

Edited and composed of: Marek Smyczek and Marcin Kaim English translation: Joanna Margowniczy

IT Publishing House

http://www.itstart.pl

email: itstart@itstart.pl

This publication has been developed in order to facilitate the assimilation of practical content related to computer networks and as a textbook supporting teaching in the professions: IT Technician and ICT.

The authors and the Publisher have made every effort to ensure that the information contained in this book is complete and reliable. However, they do not take any responsibility either for their use or for the related possible infringement of patent or copyright rights. In addition, the authors do not bear any responsibility for any damage resulting from the use of the information contained in the book. All rights reserved. Unauthorized distribution of all or parts of this publication in any form is prohibited. Making copies by xerographic, photographic method, as well as copying on a film, magnetic, optical or other medium causes infringement of the copyright of this publication.

ISBN 978-83-65645-79-1

First Edition – Piekary Śląskie 2023

TABLE OF CONTENTS  

1   INTRODUCTION................................................................................................ 11  

1.1   M AIN  C HANGES IN THE  P ACKET  T RACER  8.2 ............................................................. 11  

1.2   D ETAILED  C OMMENTS  A PPLYING TO THE  P ROGRAM  V ERSION . ...................................... 12  

1.3   K EEP ME LOGGED IN  O PTION  .................................................................................. 12  

1.4   T HE MINIMUM  S YSTEM  R EQUIREMENTS . .................................................................. 13  

2   DOWNLOADING  AND INSTALLING  CISCO PACKET TRACER ............................... 17  

2.1   D OWNLOADING FROM  NETACAD .......................................................................... 17  

2.2   INSTALLING THE  P ACKET  T RACER  (V ERSION  8.2.0) ..................................................... 23  

2.3   T HE  F IRST  R UN OF THE  P ACKET  T RACER  P ROGRAM  ..................................................... 24  

3   GETTING STARTED WITH THE CISCO PACKET TRACER ........................................ 29  

3.1   T HE  M AIN  P ROGRAM  W INDOW  ............................................................................. 29  

3.2   T HE  M AIN  A REAS OF THE  P ROGRAM  W INDOW  .......................................................... 30  

3.3   T OOLBAR  ICONS  ................................................................................................... 32  

3.4   G ENERAL  P URPOSE  T OOLBAR  ICONS  ........................................................................ 35  

4   BASICS OF WORKING WITH THE CISCO PACKET TRACER .................................... 39  

4.1   F IRST  S TEPS  ........................................................................................................ 39  

4.1.1   Working with Devices .............................................................................. 39  

4.1.2   Replacing and Adding Modules ............................................................... 40  

4.1.3   Network Cabling ...................................................................................... 45  

4.1.4   Connecting Devices.................................................................................. 47  

4.1.5   Basic Device Configuration ...................................................................... 49  

4.1.5.1   Global Configuration Mode  ............................................................................. 49  

4.1.5.2   Desktop Tools .................................................................................................. 50  

4.1.6   Check the Status of Your Configuration ................................................... 52  

4.1.6.1   Status of Network Adapter LEDs  .................................................................... 52  

4.1.6.2   IP Address Display  .......................................................................................... 54  

4.1.6.3   Inspect Tool ..................................................................................................... 54  

4.1.6.4   Command Line for PC  ..................................................................................... 55  

4.1.7   Testing Connection (Real Mode) ............................................................. 57  

4.1.7.1   Simple Way - Graphic PING  ........................................................................... 57  

4.1.7.2   Standard Method - PING via Command Line  ................................................. 58  

4.1.7.3   Advanced Graphic PING  ................................................................................. 59  

4.1.8   Testing Connection (Simulation Mode) ................................................... 61  

5   DEVICES USED TO CREATE NETWORK ............................................................... 67  

5.1   H UBS  ................................................................................................................. 67  

5.2   R EPEATERS  ......................................................................................................... 77  

5.3   B RIDGES  ............................................................................................................. 78  

5.3.1   Two‐segment Network Built with Two Hubs ........................................... 78  

5.3.2   Sample Network with a Bridge ................................................................ 80  

5.4   S WITCHES  ........................................................................................................... 83  

5.5   A CCESS  P OINTS  .................................................................................................... 86  

5.6   O THER  A CCESS  P OINT  W IRELESS  D EVICES  ................................................................. 92  

5.6.1   LAP‐PT Devices ........................................................................................ 92  

5.6.2   3702i Device ............................................................................................ 92  

5.6.3   WLC‐PT Device ......................................................................................... 93  

5.6.4   WLC‐2504 Device ..................................................................................... 93  

5.7   W I‐F I  A CCESS  R OUTERS  ........................................................................................ 94  

5.7.1   Standard Configuration of the Wi‐Fi Router ............................................ 94  

5.7.2   Configuration of Wi‐Fi Router via HTTP .................................................. 99  

5.8   D EVICES FOR  C REATING  GSM  N ETWORKS  .............................................................. 1 1 8  

5.9   H ARDWARE  F IREWALLS  ....................................................................................... 119  

5.9.1   Meraki‐MX65W Device ......................................................................... 119  

5.9.2   Meraki‐Server Device ............................................................................ 120  

5.9.3   ASA5505 and ASA5506 Devices ............................................................. 121  

5.9.3.1   ASA 5505 Device ............................................................................................ 122  

5.9.3.2   ASA 5506 Device ............................................................................................ 122  

6   BASICS OF DATA TRANSMISSION AND OVERVIEW OF NETWORK SERVICES ..... 125  

6.1   T RANSMISSION  T YPES  ......................................................................................... 125  

6.1.1   Half Duplex ............................................................................................ 125  

6.1.2   Full Duplex ............................................................................................. 127  

6.2   C ONFIGURING  N ETWORK  S ERVICES  ........................................................................ 127  

6.2.1   DHCP...................................................................................................... 128  

6.2.2   HTTP ...................................................................................................... 130  

6.2.3   FTP ......................................................................................................... 133  

6.2.4   SMTP/POP3 ........................................................................................... 138  

6.2.5   DNS ........................................................................................................ 143  

6.2.6   Firewall .................................................................................................. 148  

7   SKILL EXERCISES – PART I ................................................................................ 159  

7.1   D EVICE ‐T O ‐D EVICE  C ONNECTIONS  ........................................................................ 159  

7.1.1   Connection of Devices According to the Scheme ................................... 159  

7.1.2   Connecting Devices to the Wi‐Fi Router and Access Point .................... 160  

7.1.3   Connecting Computers That Are At Longer Distance Then 100 Meters  161  

7.1.4   Using a HUB to Connect Devices Into a Single Local Network ............... 162  

7.1.5   Using a Bridge to Limit Packet Collisions on a Local Network ............... 163  

7.2   C ONFIGURE  S ERVICES ON  S ERVERS  ........................................................................ 164  

7.2.1   DNS and HTTP Configuration ................................................................ 164  

7.2.2   Configuring DHCP and FTP .................................................................... 165  

7.2.3   Mail Server Configuration (SMTP, POP3) .............................................. 167  

8   CONFIGURING CISCO ROUTERS ...................................................................... 171  

8.1   E XPLORING THE  E QUIPMENT OF  C ISCO  R OUTERS  ...................................................... 171  

8.1.1   Series 1841 ............................................................................................ 171  

8.1.2   Series 1941 ............................................................................................ 173  

8.1.3   Series 2620XM ....................................................................................... 174  

8.1.4   Series 2621XM ....................................................................................... 177  

8.1.5   Series 2811 ............................................................................................ 178  

8.1.6   Series 2901 ............................................................................................ 179  

8.1.7   Series 2911 ............................................................................................ 179  

8.1.8   IR829 Router .......................................................................................... 180  

8.1.9   819IOX Router ....................................................................................... 181  

8.1.10   CGR 1240 Router ................................................................................... 182  

8.1.11   ISR 4321 Router ..................................................................................... 182  

8.1.12   819IOX Router ....................................................................................... 184  

8.1.13   819HGW Router .................................................................................... 184  

8.1.14   Series PT Router ..................................................................................... 185  

8.2   C ONFIGURE  C ISCO  R OUTERS  U SING THE  G RAPHICAL  INTERFACE  .................................. 187  

8.2.1   Interface Configuration ......................................................................... 187  

8.2.2   GUI‐Configurable Routing Protocols ..................................................... 192  

8.2.2.1   Static Routing  ................................................................................................ 192  

8.2.2.2   RIP Routing Protocol  .................................................................................... 196  

8.3   C ONFIGURING  C ISCO  R OUTERS IN  C ISCO  IOS ........................................................... 2 0 0  

8.3.1   Basics ..................................................................................................... 201  

8.3.2   Wizard Mode ......................................................................................... 203  

8.3.2.1   Simple Wizard Mode ..................................................................................... 204  

8.3.2.2   Advanced Wizard Mode ................................................................................ 207  

8.3.3   Basic Router Configuration Modes ........................................................ 210  

8.3.3.1   Console Mode Support .................................................................................. 210  

8.3.3.2   Using Help ..................................................................................................... 212  

8.3.3.3   View the Status of the Router ....................................................................... 216  

8.3.4   Configure Router Name, Passwords, and Message Of The Day (MOTD)  2 1 9  

8.3.5   Other Modes of Operation of the Router .............................................. 222  

8.3.5.1   Console Port Configuration ........................................................................... 223  

8.3.5.2   Configuration of Virtual Terminals (Telnet, SSH) ........................................... 224  

8.3.5.3   Interface Configuration ................................................................................. 228  

8.3.5.4   Configuration of Sub‐Interfaces..................................................................... 235  

8.3.6   DHCP Configuration ............................................................................... 236  

8.3.7   Static Routing Configuration ................................................................. 238  

8.3.8   RIP Routing Protocol Configuration ....................................................... 241  

8.3.9   EIGRP Routing Protocol Configuration .................................................. 245  

8.3.10   OSPF Routing Protocol Configuration .................................................... 248  

8.3.11   Local Definition of Router Names .......................................................... 252  

8.3.12   Save the Current Configuration ............................................................. 254  

8.3.13   Securing Your Configuration .................................................................. 256  

9   CONFIGURING CISCO SWITCHES ..................................................................... 263  

9.1   E XPLORING THE  E QUIPMENT OF  C ISCO  S WITCHES  ..................................................... 263  

9.1.1   Switch 2950 ........................................................................................... 263  

9.1.2   Switch 2950T ......................................................................................... 264  

9.1.3   Switch 2960 ........................................................................................... 264  

9.1.4   PT‐Switch  and PT‐Empty Switch ........................................................... 264  

9.1.5   Series 3560 ............................................................................................ 266  

9.1.6   Series IE 2000 ........................................................................................ 266  

9.2   C ONFIGURE  C ISCO  S WITCHES  U SING THE  G RAPHICAL  INTERFACE  ................................. 267  

9.2.1   Interface Configuration ......................................................................... 267  

9.2.2   Configuring Virtual LANs (VLANs) .......................................................... 270  

9.2.3   Enabling Communication Between VLANs ............................................ 274  

9.3   C ONFIGURING  C ISCO  S WITCHES IN THE  IOS ............................................................. 278  

9.3.1   Basic Information .................................................................................. 278  

9.3.2   Basic Switch Configuration Modes ........................................................ 279  

9.3.3   Interface Configuration ......................................................................... 279  

9.3.4   VLAN Configuration ............................................................................... 280  

9.3.5   Configuration of Virtual Terminals (Telnet, SSH) ................................... 283  

9.3.6   REP Protocol .......................................................................................... 286  

9.3.6.1   Purpose of REP .............................................................................................. 287  

9.3.6.2   Basic Concepts of REP .................................................................................... 287  

10   PHYSICAL TOPOLOGY IN THE CISCO PACKET TRACER ................................... 293  

10.1   A RRANGING  D EVICES  .......................................................................................... 301  

10.2   P HYSICAL  C ABLE  L ENGTHS AND  D ISTANCES  ............................................................. 301  

10.3   C ABLE  M ANAGEMENT  ......................................................................................... 304  

11   SKILL EXERCISES – PART II ........................................................................... 309  

11.1   C ONFIGURE  D EVICES  U SING THE  G RAPHICAL  INTERFACE  ............................................ 309  

11.1.1   Interface configuration, static routing .................................................. 309  

11.1.2   Switch Modes, VLANs Configuration ..................................................... 310  

11.2   R OUTING  P ROTOCOLS , R EMOTE  M ANAGEMENT  ...................................................... 311  

11.2.1   RIPv2 and Configuration Using Telnet, Local Name Definition ............. 311  

11.2.2   RIPv2 and Configuration Using Telnet, Local Name Definition ............. 312  

11.2.3   EIGRP and Configuration via SSH, HTTP and DNS ................................. 313  

11.3   VLAN S , R OUTER ON A  S TICK , R EMOTE  M ANAGEMENT  ............................................. 314  

11.3.1   Switch Modes, VLAN Configuration ....................................................... 314  

11.3.2   VLAN Configuration, Routing Between VLANs ...................................... 315  

11.3.3   Remote Switch Management ................................................................ 316  

11.3.4   Protocol REP in Switches ....................................................................... 317  

12   WORKING WITH LARGE TOPOLOGIES ......................................................... 321  

12.1   INTRODUCTION TO  D EVICE  G ROUPING  ................................................................... 321  

12.2   D EVICE  G ROUPING  –  D ESCRIPTION OF  T OOL  B UTTONS  .............................................. 321  

12.3   D EVICE  G ROUPING  –  S TEP ‐B Y ‐S TEP  A LGORITHM  ..................................................... 322  

12.4   M OVE A  S INGLE  D EVICE  F ROM THE  C LOUD TO THE  R OOT  L EVEL  .................................. 324  

12.5   M OVE A  S INGLE  D EVICE FROM THE  R OOT  L EVEL TO THE  C LOUD  .................................. 326  

12.6   P URPOSE OF THE  S ET  T ILED  B ACKGROUND  B UTTON  .................................................. 327  

12.7   R ENAME A  C LOUD  .............................................................................................. 329  

12.8   M ULTIUSER  M ODE  ............................................................................................. 329  

13   DHCP PROTOCOL FOR IPV4 ......................................................................... 339  

13.1   INTRODUCTION TO  DHCP .................................................................................... 339  

13.1.1   DHCP Basics ........................................................................................... 339  

13.1.2   DHCP Phases.......................................................................................... 340  

13.2   C ONFIGURING  DHCP  ON THE  S ERVER  .................................................................... 345  

13.2.1   Configuring the DHCP Server Service ..................................................... 345  

13.2.2   Erasing DHCP on the Server ................................................................... 348  

13.2.3   Disabling DHCP on the Server ................................................................ 348  

13.2.4   Deleting DHCP Address Pool on the Server............................................ 348  

13.3   C ONFIGURING  DHCP  ON  Y OUR  R OUTER  ................................................................ 349  

13.3.1   Configure the Router (DHCP Server) Address Pool ................................ 351  

13.3.2   Viewing the Assigned IP Address Array in DHCP ................................... 353  

13.3.3   Verifying the DHCP Service Is Working on the Router ........................... 353  

13.3.4   Deleting the DHCP Configuration on the Router (DHCP Server) ............ 355  

13.3.5   Deleting DHCP Configurations on Computers (DHCP Clients) ............... 355  

13.4   DHCP  ON A  N ETWORK WITH  M ULTIPLE  R OUTERS  .................................................... 355  

13.4.1   Set Up an Intermediary Router .............................................................. 356  

13.4.2   Start DHCP and Configure the Address Pool .......................................... 357  

13.4.3   Check the Array of Assigned IP Addresses on the Router ...................... 358  

13.5   C ONFIGURING  DHCP  ON THE  W IRELESS  R OUTER  ..................................................... 358  

13.5.1   Configuring DHCP on the WRT300N ...................................................... 358  

13.5.2   Configuring DHCP Based on MAC Addresses ......................................... 364  

14   SKILL EXERCISES – PART III .......................................................................... 371  

14.1   G ROUPING  D EVICES AND  C OMBINE  T WO  INSTANCES OF THE  P ROGRAM  ....................... 371  

14.1.1   Grouping Devices ................................................................................... 371  

14.1.2   Device Grouping and Multiuser Function .............................................. 372  

14.2   DHCP  FOR  IP V 4 ................................................................................................ 373  

14.2.1   Configuring DHCP on the Server ............................................................ 373  

14.2.2   Configuring DHCP on the Router ........................................................... 374  

14.2.3   Configuring DHCP on the Wireless Router ............................................. 375  

14.2.4   DHCP Configuration on a Server That Is on a Remote Network ............ 376  

15   MISTAKES MADE DURING NETWORK CONFIGURATION  ...................... 381  

15.1   W IRING OR  P ORT  E RRORS .................................................................................... 381  

15.2   D EVICE  R ELATED  E RRORS  ..................................................................................... 383  

15.3   IP  A DDRESSING  E RRORS  ...................................................................................... 383  

16   LIST OF THE SAMPLES AND SKILL EXERCISE’S SOLUTIONS ............................ 391  

16.1   T HE  S AMPLE  S OLUTION  F ILES  ............................................................................... 391  

16.2   T HE  S KILL  E XERCISE ’S  S OLUTIONS  .......................................................................... 393 

1 INTRODUCTION

The book PACKET TRACER FOR YOUNG BEGINNERS ADMINS contains advice for people who want to learn how networks work and the hardware that makes up the modern network architecture. Beginners will learn how to download the simulator software and how to start working with it.

The reader will find here the basics of configuring network devices. You will learn about network services such as TELNET, SSH, FTP, EMAIL, DHCP, DNS and routing protocols RIP, EIGRP, OSPF. Learn how to design and deploy VLANs. The authors, when describing the issues of administering computer networks, use many examples and exercises.

The book is an updated compilation of the publications of our Publishing House from the Packet Tracer series for CISCO courses, has a described changed interface of the currently latest Packet Tracer software and contains a set of new examples and exercises. In order to facilitate learning, the authors have prepared numerous examples and exercises supporting the teaching process, which have been placed on a special website of our publishing house, at the following address: http://ptfyba.itstart.pl . To get full access to the files, you must log in with the login: ptfyba and password: ptfa!BEG . The files have been divided into two categories: examples and exercises, and are located in subdirectories, with the names: ( examples and exercises )

Note: To open and use them, you must have Packet Tracer at least version 8.2.0 installed. The publisher and authors are not responsible for the malfunction of files in other versions of Packet Tracer.

In this book there are definitely some small bugs, according to Murphy's Law, if something goes wrong, it will happen.

1.1 Main Changes in the Packet Tracer 8.2 On July 28 th , 2022 the version 8.2 of the program Packet Tracer was released. The main changes compared to the previous version are:

 simplified way of logging in ( the option of logging in the visitor is not available any more ),

 the mistakes have been improved (e.g. in VTP the Transparent mode works correctly),

 the visualization of transferring devices and wiring in the patch cabinet.

1.2 Detailed Comments Applying to the Program Version.

 The files made in Cisco Packet Tracer in 7.2.2 version or older might work differently in Cisco Packet Tracer 8.2 version.

 Depending on the efficiency of your computer, running Packet Tracer Activity ( PKA ) files or Packet Tracer ( PKT ) might take a few minutes!

 Not all offered functionalities work correctly!

1.3 Keep me logged in Option

„Keep me logged in” option was designed to ensure the access (for 3 months) to Cisco Packet Tracer without the necessity of logging in again each time .

Figure 1.1 Keep me logged in option

Using „ Keep me logged in ” option is recommended for private computers. If you use public or any shared computer, DO NOT use “Keep me logged in” option or log out before closing Cisco Packet Tracer to unable the other users of the computer the access to PT using Your credentials.

1.4 The minimum System Requirements.

Part 1. System requirements for Cisco Packet Tracer 8.2 (64 bit).

 operating systems: Microsoft Windows 8.1, 10, 11 (64bit), Ubuntu 20.04 LTS (64bit), macOS 10.14 or newer versions

 amd64(x86-64) CPU

 4GB of free RAM

 1.4 GB of free disk space

Part 2 . System requirements for Cisco Packet Tracer 8.2 (32 bit).

 operating systems: Microsoft Windows 8.1, 10 (32bit)

 x86 compatible CPU

 2GB of free RAM

 1.4 GB of free disk space

2.1 Downloading from NETACAD

How to obtain Cisco Packet Tracer?

Cisco Packet Tracer is available free of charge to all Cisco Networking Academy instructors, students, and alumni.

Please follow these instructions to download the software from the NetAcad.com learning environment:

1. Log in to Cisco NetAcad.com;

2. Select Resources  Download Packet Tracer ;

You can also sign up for the free “ Getting Started with Cisco Packet Tracer ” on SkillsForAll.com to learn how to download, install, and get started. What if I do not have NetAcad.com account?

The latest version of Cisco Packet Tracer requires user authentication. A NetAcad.com or a SkillsForAll.com account is required to sign in when you launch Cisco Packet Tracer. Remark. Due to the possibility of infecting the program, it is not recommended to download the program from other unknown Internet resources than Cisco Networking Academy . You can use the latest versions of Cisco Packet Tracer ( 8.2.0 ) in two ways: as a Guest or when you log in to the Cisco Networking Academy:

 way one: as a guest;

 the second way: as a student of the Academy;

The first method is characterized by the fact that the number of records of practice PKT and PKA files is limited. The Packet Tracer program is free of charge and can be used without restrictions (after obtaining an account in the Academy).

To use the second way , i.e. to use the program without restrictions, you should:  

 Register for the course "Getting Started with Cisco Packet Tracer"

 Create your own Cisco Networking Academy account

 Log in to your Academy account

Alternatively, download the correct version of the installation file and install the program if Cisco Packet Tracer is not installed in the lab.

Start the program for the first time (any questions in the dialog boxes should be answered positively).

Figure 2.1 Cisco Networking Academy Website Window

Step 2. On the official website of the Academy, at the bottom of the Academy, find an item called [ Packet Tracer ] and then click on it

Figure 2.2 Packet Tracer on the Cisco Networking Academy website

Figure 2.3 Cisco Packet Tracer – View courses Button

Step 3. A page will appear informing you about the enrolling the Getting Started with Cisco Packet Tracer

Figure 2.4 Cisco Packet Tracer website

Step 4. A page will appear informing you about the procedure for Getting Started with Cisco Packet Tracer

Figure 2.5 Button [Get Started] in Getting Started with Cisco Packet Tracer

Figure 2.6 Button [Continue] in Getting Started with Cisco Packet Tracer The course Getting Started with Cisco Packet Tracer is free - No purchase required, anytime. Estimated time to complete, but finish it in your time - 2 Hours. Level of the course: beginner.

Step 5. Log in with your existing account or sing up, if don’t have an account.

Figure 2.7 Log in or Sign up screen

Step 6. Sing up, if don’t have an account.

Figure 2.8 Sign Up screen

Figure 2.9 Sign Up screen

Step 6. After registering, you can login to your account

Figure 2.10 Log in screen

Step 7. Select Resources  Download Packet Tracer

To do this, find the top menu and [Resources] and then select [Download Packet Tracer].

Figure 2.11 Menu [Resources] in Networking Academy

Step 8.   Select the appropriate operating system type and platform (32-bit or 64-bit) and download the appropriate file.

Figure 2.12 Saving install file on your local disk

2.2 Installing the Packet Tracer (Version 8.2.0) Step 1. Run the installer  CiscoPacketTracer_820_Windows_64bit.exe or any other suitable version of your choice.

Step 2. Accept the License Agreement

Figure 2.13 Accepting the License Agreement

Step 3. Select Destination Location (the best practice principle – leave the default setting)

Figure 2.14 Selecting the Destination Location

Step 4. Select Start Menu Folder (the best practice principle – leave the default setting)

Figure 2.15 Selecting the Start Menu Folder

Step 5. Select Additional Tasks (the best practice principle – leave the default settings)

Figure 2.16 Selecting the Additional shortcuts: Desktop and Quick Launch Step 6. Continue the installing process

2.3 The First Run of the Packet Tracer Program Step 1. The first run of the program – boot logo.

Figure 2.17 The first run of the program – boot logo.

Step 2. The first run of the program – should the Multi-user mode be activated during application start? (it doesn’t matter what is chosen).

Figure 2.18 The first run of the program – activating a multi-user mode Step 3. The first run of the program – it is necessary to enable the „ Keep me logged in ” option.

Step 4. The first run of the program - choose „ Networking Academy ”.

Figure 2.19 The first run of the program - choosing Networking Academy Step 5 . The first run of the program - you should check if the newest version of the Packet Tracer has been run. From the main menu choose Help  About and check the version.

Figure 2.20 The first run of the program – check the version.

of Cisco Packet Tracer.

3.1 The Main Program Window

When you start Cisco Packet Tracer , the default view of the main program window will appear, shown in the figure, where the most important areas of the packet tracer are described and shown below.

Figure 3.1 The main Packet Tracer window

3.2 The Main Areas of the Program Window Below there are brief descriptions of the areas of the Main window.

Table 3.1 Descriptions of areas of the main Packet Tracer window

3.3 Toolbar Icons

Below, there are brief descriptions of the icons in the toolbar.

Table 3.2 Icon descriptions in the Packet Tracer toolbar

3.4 General Purpose Toolbar Icons

Below, there are brief descriptions of the icons in the general use toolbar.

Table 3.3 Icon descriptions in the Packet Tracer General Utility Toolbar

4 Basics of Working with the Cisco Packet Tracer

4.1 First Steps

This chapter shows you how to create your first network connections, basic devices, necessary wiring, and appropriate device configurations.

4.1.1 Working with Devices

Suppose the first task will be to directly connect two computers with a network cable without additional devices. What will you need? Of course, two computers that you should look for in the device block in the End Devices section. If you want to diversify the task a little, you can combine a desktop computer with a laptop.

If you want to add a device, grab it with the left mouse button and drag it into an empty workspace of the program. The end result should look like the following figure.

Figure 4.1 Devices placed in the workspace

Of course, at any time you can move any object or selected group of objects to another place in the workspace. To do this, hold the element and drag it to another place.

Figure 4.2 Moved devices to other locations in the workspace It may also happen that when working with placing elements on the matrix, some device turns out to be superfluous or redundant and there will be a need to remove it. Then, on the top toolbar, click the Delete button then the cursor turns into a cross and you can indicate the device to be removed, as shown in the figure below. After doing this, the delete mode is still open, so to return to normal operation, press the Esc button on the keyboard.

Figure 4.3 Remove an unnecessary device

4.1.2 Replacing and Adding Modules

Theoretically, devices are prepared for connection, however, sometimes there is a need to install a different network adapter in the device than the one that is in its equipment by default, which must be done before making the wiring. These steps are described in this section of the book.

By default, computers have Fast Ethernet network adapters with a bandwidth of 100Mbps installed. Assuming that you are connecting computers in the same technology, but with a higher bandwidth, i.e. 1Gbps. To do this, both devices need to replace the current network adapters with new ones. To do this, it is required to click on the icon of the computer located in the workspace, which will result in the window shown in the following figure.

Figure 4.4 Desktop configuration window

The window consists of four tabs, of which you will need the first of them, i.e. Physical, to replace the network card. It consists of two parts: on the left side there are components that can be installed, and on the right there is a view of the central unit of the computer. The Packet Tracer is a tool that almost realistically reflects the real-world environment, so to remove the current network adapter, you must first shut down the computer. To do this, place the mouse cursor near the power button and click on it, after which the LED light will turn off, which means that the central unit is turned off.

Figure 4.5 Disabling the central unit of the PC.

After the computer is turned off correctly, you can proceed to remove the unnecessary network adapter located in the central processing unit. To do this, move the computer view slightly down so that you can see the network adapter, then grab it with the left mouse button and move it to the left, above the list of devices to install, and then release the mouse button.

Figure 4.6 Remove a network adapter from the computer's central processing unit After a while, the slot in the central unit should be empty, which means that the network adapter has been removed, as shown in the figure below.

Figure 4.7 An empty slot on a desktop computer when you remove a network adapter

At this point, you can proceed to the installation of the correct card, but before that you need to make an overview of all devices that can be installed and connected to the central unit. The type of device can be recognized by the photo, and its full specification by its description. The devices have been divided into the following groups:

1. Ethernet UTP network adapters:

 PT-HOST-NM-1CE – Ethernet port, designed for working with copper media, which can be used for LAN connections with a bandwidth not exceeding 10 Mbps, able to support up to six PRI connections of ISDN lines - 24 synchronous / asynchronous ports.

 PT-HOST-NM-1CFE – Fast-Ethernet port, designed to work with copper media. Ideal for a wide range of LAN applications. Single network modules with automatic detection of 100BaseFX(copper) Ethernet ports. The version supports virtual LANs (VLANs).

 PT-HOST-NM-1CGE – Gigabit Ethernet port, providing copper connectivity in LAN networks as well as for access routers with 1Gbps speed. The module is supported by Cisco 2691, Cisco 3660, Cisco 3725 and Cisco3745 series routers. This module has one Gigabit network

2. Ethernet Fiber Optic Network Adapters:

 PT-HOST-NM-1FFE – Fast-Ethernet port using fiber optic media. Ideal for a wide range of LAN applications, high-speed Ethernet modules supporting multiple functions in a 10/100Mbps Internet environment with automatic port detection.

 PT-HOST-NM-1FGE – Gigabit Ethernet port, providing optical connectivity with 1Gbps bandwidth for access routers. The module is supported by Cisco2691, Cisco 3660, Cisco 3725 and Cisco3745 series

3. Wireless network adapters:

 Linksys-WMP300N –  Linksys 2.4 GHz wireless interface, suitable for connecting wireless networks. The module supports Ethernet protocols for connection to LAN-WIFI.

 PT-HOST-NM-1W –  2.4 GHz wireless interface, suitable for connection to wireless networks. The module supports Ethernet protocols for connection to the LAN.

 PT-HOST-NM-1W-A – 5GHz wireless interface, suitable for connection to 802.11a wireless networks. The module supports protocols that use Ethernet to connect to the LAN.

4. Calling cards:

 PT-HOST-NM-1AM – A calling card equipped with two RJ-11 connectors that are used for basic dial-up service connections. It uses one port to connect to a standard phone line, and the other port can be connected to the base analogue line for use when the modem is at rest.

 PT-HOST-NM-3G/4G – GSM telephony card providing access to the 3G/4G generation wireless network.

5. Other external devices:

 PT-HEADPHONE – Headphone output allows you to listen to music and sounds from your computer.

 PT-MICROPHONE – Microphone input that allows you to record audio.

 PT-CAMERA – A device that allows you to capture images and videos.

 PT-USB-HARD-DRIVE –  USB hard drive, external storage space. Please note that the peripherals listed in position 5 are not connected to the expansion socket, but to the USB or MINI-JACK port in the computer case, as shown in the figure below.

Figure 4.8 Additional peripherals connected to the computer Returning to the main content of the task (i.e. installing a network card based on copper media with a bandwidth of 1 Gbps in the computer), in this case you should mount network cards in both computers: PT-HOST-NM-1CGE.

4.1.3 Network Cabling

Once your computers have expansion cards of the appropriate standard that provide bandwidth at a certain speed, you can turn on the central processing units and proceed to connect the hardware.

Before connecting the equipment, the basic types of wires that will be used for this purpose will be discussed. In order to display all types of wires, click the lightning-like icon (Connections) in the hardware block and the wiring department.

Figure 4.9 Entrance to the network cabling department

After clicking on the icon, on the right side all available types of wires that you can use as they are displayed. Due to the fact that the program can run on computers with different resolutions and can be opened in a smaller window, not all wires will be immediately visible. To do this, either use the horizontal slider to move the current view or stretch the window size so that you can see all the devices at once. Ways to work with this block are shown in the figure below.

Figure 4.10 Move the current view and stretch block size: wiring When the wiring block takes a sufficient size, all the wires that we will use in a moment will appear in it, as shown in the figure below.

Figure 4.11 All cable icons, usable in the program

We will now discuss the meaning of the icons that symbolize the type and standard of a given cable:

 Automatic cable - using this cable, it will automatically adapt to the network card installed in the device, does not require the user to have basic knowledge of cabling.

 Console cable - used to connect computers to network devices such as routers, switches to configure them through Terminal Services.

 UTP cable (straight twisted pair cable)   - one of the most commonly used cables of general application for connecting devices such as: computer-switch, switch-router, etc.

 UTP cable (cross-over twisted pair cable) - as in the above case, but to connect two identical groups of devices as: computer-computer, switch-switch, router-router.

 Fiber optic cable - for general applications where the use of optical media is required.

 Telephone cable - for use in telephone calls (e.g. for connecting an analogue phone to a VoIP gateway).

 Coaxial cable - used in cable networks and as a signal cable in terrestrial and satellite television.

 Serial cable (clock speed)   - for serial connections in WAN networks.

 Serial cable (without clock speed) - for serial connections in WAN networks.

 USB cable – to connect to devices via USB.

and switches console cables in your lab.

 IoT Custom Cable – it is a cable that allows you to create computer networks that will contain uniquely identifiable IoT (Internet of Things) devices that can directly or indirectly collect, process and send data.

4.1.4 Connecting Devices

The previous section describes typical devices and network cabling, and this subsection will describe how to connect network devices.

The first way is to use an automatic cable. From the cable group, select and click one of the computers. In the figure you can see that the wire has been connected to it and now you need to point the cursor towards the second of them, after which you can click the left mouse button again.

Figure 4.12 Connecting two devices via an automatic cable After a while, a wire will be connected between the computers, in the form of a dotted line, which is characteristic of a UTP patch cable in the Cisco Packet Tracer.  Basics of Working with the Cisco Packet Tracer Program

Figure 4.13 Connected computers via UTP patch cable

However, it will not always be possible to use an automatic connection, because, for example, if there is a need to insert it into the appropriate port, and not into the first free one, this way will be unreliable. Therefore, another way is presented, explaining how to directly use a cable of a given type, without using an automatic connection. First of all, you should choose the UTP patch cable , point the cursor over the first computer and left-click, and a pop-up menu appears from which to select the appropriate port for your connection type, in which case it will be Fast Ethernet. Then drag the cable to the other device and select the appropriate port.

Figure 4.14 Connecting devices via manual mode

4.1.5 Basic Device Configuration

After making the appropriate connections between the devices, for the proper operation of the network, its configuration is required. For proper operation of the LAN (local area network), it is enough that each device has a unique IP address and subnet mask. This section does not describe the principles of building IP addresses, address classes and dividing addresses into private or public. The subsection describes the necessary conditions to be met when addressing IP addresses. In this case, all devices must have the same class address and the same network mask but with a different host ID. This example uses a network with the address 200.200.200.0 and a network mask of 255.255.255.0 (another notation is: 200.200.200.0/24 , which means that the mask consists of 24 ones (24 bits)).

4.1.5.1 Global Configuration Mode

Depends on clicking the icon of the computer to be configured, and then the following window opens with the Config tab active.

Figure 4.15 Config tab of the PC configuration window

On the default tab in the left window, click on the interface to which the IP address will be assigned, in this case it will be FastEthernet0.

Note: To switch to static addressing, type the network address in the IP Address field, type

200.200.200.1 and Subnet Mask the default network mask for this network class, which is

255.255.255.0 . After doing this, basically, the computer was prepared to work on the network.

Figure 4.16 Assigned IP address and network mask to the computer

4.1.5.2 Desktop Tools

The second method of configuring the device is to go to the virtual desktop of the computer where it can be configured. After clicking the computer icon, with the left mouse button, go to the Desktop tab and click on the first of the available icons – IP Configuration.

Figure 4.17 Computer desktop contents

After a while, a window with the same name as the selected icon on the computer's desktop appears. Select Static and type the IP address and network mask.  Basics of Working with the Cisco Packet Tracer Program

Figure 4.18 Computer Configuration Through IP Configuration It should be remembered that no matter which method the configuration of computers was performed, it is important that everyone who will have to work on the network has an IP address and a mask configured.

4.1.6 Check the Status of Your Configuration

When working with the program, at various stages of working with the network, you should check the configuration status of the devices that make up it.

4.1.6.1 Status of Network Adapter LEDs

The basic element used for verification is to check the status of the network adapters of the devices visible at the ends of the cables connecting them.

Figure 4.19 Port status of connected network devices

The LEDs at both ends should be green . What if this is not the case? There may be several reasons for this... Here are the most likely causes:

 Incorrect wire (e.g. in this case, if a straight wire was used).

 Network device disabled (via power button).

 Disabled device port ( On must be selected, which is described as Port Status for the network adapter or interface of the selected device).

 Different speed of network adapters of connected Bandwidth devices (the best choice is to select Auto ).

 Different types of Duplex transmission (the best choice is to select Auto .

Figure 4.20 Conditions for correct configuration of computer ports

4.1.6.2 IP Address Display

When the port LEDs are green and the physical devices are running, you can check the IP address of the computer that is visible on the logical topology. The first and fastest way is to set the mouse cursor over the icon of the computer whose IP, you want to display for a while and after a while a dialog box is displayed in which you can see the basic parameters (the subnet mask, MAC address, default gateway address, DNS server address, as well as physical location will also be displayed), as shown in the figure below.

Figure 4.21 IP address and network mask of the computer displayed

4.1.6.3 Inspect Tool

Another way is to use the Inspect tool from the top tool tray and left-click on the computer. From the context menu, select Port Status Summary Table , as shown in the figure below.

Figure 4.22 Use inspect to display your computer's IP address After a while, a window will appear in which all the necessary configuration data will be presented.

Figure 4.23 Computer Port Array

4.1.6.4 Command Line for PC

The command line is designed for advanced people who have more experience working with a real computer environment. These people often use the command line to display the IP address of the computer or to configure the PC or SERVER device. The Cisco Packet Tracer implements a console that offers a poorer list of commands compared to the Console of the Microsoft Windows family, but a list of these commands for basic tasks is quite enough. To start the console for a computer, you must left-click on the computer, then go to its desktop and select a tool called Command Prompt.

Figure 3.4.24 Command line icon available on the desktop of your PC After opening the command line, you can first check the commands available in the console by typing help or ?, after which you should press Enter . All available commands that can be used will be displayed.

 Basics of Working with the Cisco Packet Tracer Program

Figure 4.25 Displaying a list of available commands at the command line To view the IP address configuration of the computer, use the ipconfig command, or (more specifically) ipconfig /all .

Figure 4.26 Displaying the IP address of the computer via the command line

4.1.7 Testing Connection (Real Mode)

If you want to test the correctness of the connection along with the configuration, you can use various tools.

4.1.7.1 Simple Way - Graphic PING

The first way is to use a special tool available from the Add Simple PDU icon. When you select the Add Simple PDU icon an envelope will be "glued" to the cursor, which must be "added" to the computer that is to send the test signal (selection of the so-called source host).

Then click "add" the envelope to the target computer (selecting the so-called destination host), as shown in the figure below.

Figure 4.27 Sending simple test information

When everything is connected and configured correctly, a red icon should appear in the field located in the lower right corner of the program window, symbolizing the sending of the package, and next to it the Successful status.

Figure 4.28 Successful delivery of the test package

Sometimes, however, especially when working with larger networks, it may turn out that the network configuration is correct, but the status takes the form of Failed. This is because only one test packet is sent during this type of activity, which for various reasons may not be delivered correctly (e.g. the ARP or routing protocol process has not yet been completed).

Then you do not need to send a new test package, but to refresh it correctly. To do this, point the mouse over the icon of the sent packet and double-click it with the left mouse button. After a while, the In Progress status will be displayed, and if everything is correct, it should change to Successful . This is illustrated in the figure below, if after several sent attempts the status still assumes the Failed status , it means that you need to check the correctness of the wiring or configuration of the devices.

Figure 4.29 Refreshing a test package

If you want to be 100% sure that the transmission works correctly in both directions, you can perform the same test, only the other way around. To do this, proceed in the same way as above, but change the order of the indicated computers. After a while, the status in the second case should also get the Successful state , as the figure below illustrates.

Figure 4.30 Checking the connectivity test in both directions

4.1.7.2 Standard Method - PING via Command Line

A more professional way to perform a connectivity test between devices is to use the command line, as if you were to display your computer's IP address. When you open the command line, type ping in the console, and after the space bar, the IP address of the computer to which you want to send the test information. In this case, it will be ping

200.200.200.2 . After a while, four test packets will be sent automatically, and if the connection is correct, then four responses. Lack of response, indicates incorrect connection

Figure 4.31 PING connection test

4.1.7.3 Advanced Graphic PING

When testing a connection, the Cisco Packet Tracer has a number of tools designed to do so. Another of them is advanced graphic Ping, if you want to use it, select Add Complex PDU from the toolbar.

Then, as in the standard graphics ping, click the source computer, and then the Create Complex PDU dialog box opens, as shown in the figure below. An important element to check is the Outgoing Port field, which should contain the interface from which the PING is to be sent, in this case it will be FastEthernet0 (you can also select Autoselect Port ).

Next, you can select the service that needs to be checked, in this case it will be PING and fill in the Destination IP Address : field (or click with the left mouse button on the target computer and the field will be filled in automatically).

An important element is to fill in the Sequence Number field (equivalent to the amount of sending test information), Size (the size of test information, expressed in bytes), as well as in the Simulation Settings section, select options (enter parameters appropriate for a single or multiple test): ( One Shot ) or if ping is to be sent cyclically, select the option ( Periodic ) and specify what, how many seconds – option ( Interval ).

Figure 4.32 Defining complex ping parameters

As in the previously described tests, in the lower right corner of the program window, you should see the Successful information, which is appropriate for the correct delivery of test information.

Figure 4.33 Correct provision of test information

4.1.8 Testing Connection (Simulation Mode)

The Cisco Packet Tracer also allows you to test in simulation mode, i.e. with visualization of network operation. To switch to simulation mode, use the button in the lower-right corner of the screen (Realtime or Simulation mode), as shown in the figure below.

Figure 4.34 Switch From Realtime to Simulation

After doing this, the Simulation Panel appears on the right side of the program window, in which all services and protocols to be tested are visible at the bottom of the window. However, if a simulation were made with these settings, too many test packets would be transmitted at once, and as a result, the simulation itself would be illegible.

Figure 4.35 Simulation Panel window

If you want to test only the correctness of the connection, it is enough to simulate the ICMP protocol itself. To do this, click on the Edit Filters button, then to deselect all selected protocols, left-click Show All/None , and then ICMP.

Figure 4.36 Selecting protocols for simulation

Legend:

1 – Simulation Panel

2 – Event List Filters

3 – Edit Filters

After that, you should proceed as it was in the mode of sending a simple graphic PING, i.e. click on Add Simple PDU and proceed in the same way as in Realtime mode (click on the source computer, then the destination computer). After a while, an envelope will appear in the workspace above the source computer, in the waiting state – the prepared package for shipment.

Figure 4.37 Ready-to-ship test package in Simulation mode After completing the described actions, the ICMP package that has been prepared for shipment appears in the Simulation Panel window. At its bottom there is a slider through which you can set the speed of the simulation by moving it to the right or left. To begin with, it is recommended to leave the default position of the slider, after which you can press the Play button to start the simulation.

Figure 4.38 Simulation Panel view

After the simulation starts, the envelope moves from the source computer towards the target computer, and after reaching the goal (which is tantamount to sending a Ping query), the packet should be reversed towards the source computer (which is equivalent to sending a response to the Ping query).

Figure 4.39 Graphical transmission of the PING package

Eventually, when the response is delivered to the sender, the icon at PC0 should appear, as in the figure below.

Figure 4.40 Graphical designation of the received PING packet This means that the response is delivered correctly, while if a different icon is displayed, it means that the return packet has not been received. In the upper part of the simulation panel, you can also observe its individual stages, as shown in the figure below.

Figure 4.41 Individual simulation steps in the Simulation Panel window

5 Devices Used to Create Network

We have already discussed the configuration of PCs and tested the first connections. Now we will deal with slightly extensive networks, consisting of several end devices, exchanging information with each other.

5.1 Hubs

A network hub (commonly called a hub ) is a device (also called a repeater) that allows you to connect many network devices to a computer network with a star topology. The hub is dedicated solely to transmitting and amplifying electrical signals from one port to all other network ports. The hub creates conflicting domains. A collision domain is a part of the network in which the transmission must be carried out by the device in a way that excludes transmission by other devices at the same time.

Types of network hubs can be found in the Hubs section, after selecting the Hubs section, 3 devices are available: Hub , Repeater and Coaxial Spliter . In our case, you will need the first device that can be placed in the working area.

Figure 5.1 Network devices available in the Hubs section

After clicking on the hub with the left mouse button, you should enter its settings, but it is an unmanaged device and cannot be configured (hence the Config tab is empty), but on the Physical tab, you can exchange network modules in it, exactly the same as it was in a desktop computer.

Figure 5.2 Physical view of the hub available in the program By default, the hub is equipped with the six Fast Ethernet network interfaces and has an additional four empty ports, which allows for a maximum of ten end devices. In this subsection there is no description of the replacement of components, but only the construction and operation of the network based on this type of device will be presented. To begin with it, 100% of its already installed interfaces will be used to create a LAN consisting of five PCs and one network printer. The arrangement of devices in the workspace is arbitrary, and the following figure illustrates an example of their arrangement.

Figure 5.3 Arrangement of network devices in the program workspace After you have placed all the devices in the workspace, you can proceed to connect them. Of course, you can use the tool for automatic cable selection for this purpose or do it manually. When using the second method, keep in mind that you should use a Copper Straight-Through

When computers are connecting to the hub manually, remember to select additional ports for given devices.

Figure 5.4 Manually connect your computer to the hub

When all devices have been connected, all LED should turn green, and the topology should look as shown in the figure below.

Figure 5.5 Correct connection of devices with the hub

Assumption: address class A 10.0.0.0/8 used, i.e. with network address 10.0.0.0 and mask

255.0.0.0. A device that we have not yet encountered in our book is a network printer, its physical appearance is shown in the figure below. Of course, the network card can be replaced with another type.

Figure 5.6 Physical appearance of a network printer

The IP configuration window of the network printer is illustrated in the figure below. On the Config tab, left-click on the printer port (in this case it will be Fast Ethernet ) and configure the network address of the printer.

Figure 5.7 Network Printer IP Setup

When the network begins to take on slightly larger sizes, it is worth controlling it, and thus it is worth using comments in the form of notes that we can place in the work area of the program. For this purpose, we use the icon tool located on the toolbar – it is Place Note .

You can use notes to identify computers faster. The created notes, containing the IP addresses of network devices, on the program board are illustrated in the following figure.

Figure 5.8 Notes placed on the program board

In the example presented above, all devices have been given IP addresses and network masks, network tests should be carried out. The network has been configured correctly, but to be sure you need tools that will be used to check the status of the hub, which is Inspect . After selecting this tool and clicking the hub with the left mouse button, the following window is displayed, where you can observe the status of all ports of the network device.

Figure 5.9 Hub port status displayed

After confirming the status of the hub, you can enter the simulation mode. In simulation mode, you can use ICMP to check the route of packets. For example, you need to send a test package from PC0 to a Printer0 network printer. During the simulation, when the test package passes through the hub, it separates into as many parts as there are devices connected to the hub and each of them goes to the device connected to a given port. This situation is not a mistake, but actually reflects the operation of the hub, which distributes input information to all active ports, without analyzing to which host they were addressed.

Figure 5.10 Cloning process of an ICMP packet passing through a hub When the separated packets reach their goal, they are rejected by devices to which the test information was not addressed, as shown by the red " X " crosses displayed on the supplied envelopes. In this case, the packets are received only the "recipient" is a network printer, above which a green " V " or no " X " is displayed.

Figure 5.11 Test information provided for the network printer After the package is delivered to the printer, the response to the query sent from PC0 will be transmitted. Due to the fact that the response will also pass through the hub, it will also be sent to all other computers, but it will only be accepted by the sender of the query, which will be marked with a "V" on pc0.

Figure 5.12 Delivering a response from a network printer to a PC0 After the simulation is complete, you can check the Simulation Panel window, specifically the Event List . Compared to the simulation carried out on only two connected computers, you can see that there are many more events, and they correspond to all stages of the simulation.

Figure 5.13 A list of the events of the simulation

In addition to the advantage that the hub has, which is the speed of operation and the ease of adding more hosts to the network, it is characterized by a huge disadvantage, which is the inability to transmit two packets at the same time.

This phenomenon is called a collision.

Below is a simulated collision. To perform the simulation, it is best to remove the previous package and add two packages from scratch. Assume that PC0 and PC2 will want to communicate with the printer at the same time.

Figure 5.14 Waiting packages to start the simulation

To validate the addition of packages, do so in the Event List event window, as shown in the figure below.

Figure 5.15 Visible packages in the Event List window

After checking all the guidelines described above, you can run the simulation. Packages begin to move towards the hub at the same time. When they reach the central point of the network, a collision occurs between them, which in the program is symbolized by red flare, as illustrated in the figure below.

Figure 5.16 Collision inside the HUB

Due to the hub feature, the packets will be duplicated according to the number of ports used and in an unreadable form for terminal devices will be delivered to computers and the printer, as shown in the figure below.

Figure 5.17 Duplicate collision packages delivered to terminal equipment

5.2 Repeaters

A device with the same properties as a hub is a signal amplifier (repeater). By default, it has two ports of the same type.

With the help of a repeater, it is certainly impossible to create a network with a star topology, because you can connect only two devices to it. However, it can be used to amplify the signal and increase the distance between computers.

Figure 5.18 Repeater with Fast Ethernet and Fiber Optic port This example assumes that two computers need to be connected to each other, but the distance between them is about 500 m, which is more than 100 m. According to standards and norms, the length of the cable (Ethernet segment) should not be longer than 100 m, so use devices that amplify the signal between network segments, e.g. two repeaters. All devices are placed in the work area of the program, as shown in the figure below.

Figure 5.19 Deployed network devices

In order to configure networks containing repeaters, add them to the network, left-click on the icon of the first repeater, then replace one of the ports from Ethernet to optical and do the same with the second repeater.

The connection should be as shown below. The optical wires in the area of the main board of the program take the colour red .

Figure 5.20 Correct connection of network devices

You can then proceed to perform device addressing to finally perform link tests in both Realtime and Simulation mode.

Figure 5.21 Link test in Simulation mode

5.3 Bridges

Bridges are used to limit the collision domain, e.g. to divide one LAN segment into two collision segments (domains) or to separate physical networks, e.g. copper cable network from fiber optic cable network.

5.3.1 Two-segment Network Built with Two Hubs

Before it is presented what is the point of using bridges, this subsection will describe how a two-segment network made of two hubs behaves. Hubs with Ethernet ports are connected to each other by a patch cable.

Figure 5.22 Two connected LAN segments

After going to the simulation and sending the test packet from th e P C3 to the p r in ter , w h ich is in the same segment, then due to the feature of the hub, it will also be delivered to the second segment, it will also be duplicated to all connected ports. So you can see that the collision domain (the area where packet collisions can occur) has expanded to include a second LAN segment.

Figure 5.23 Collision domain covering two LAN segments

If the simulation comes to successful, you will notice that the printer correctly accepted the sent packet, after which it will send a response to PC0, the response, like the query, will also be redundantly distributed to the second LAN segment.

Figure 5.24 Distribute packets to two network segments

5.3.2 Sample Network with a Bridge

To limit a collision domain to a single LAN segment, you can use a bridge . Bridge devices are located in the Switches section , which is a device in the list of available devices called PT-Bridge .

Figure 5.25 Select a bridge from the list of switches

The physical view of the bridge in the Cisco Packet Tracer looks like the following figure. The device is not configurable, it has two Ethernet ports, which of course can be exchanged for others according to the previously learned methods.

Figure 5.26 Physical view of the network bridge

between the two hubs using the Delete tool , available has a toolbar. After that, in the working area you need to put a bridge and connect the hubs with the bridge, the patch wire. LED sirens next to the bridge first light up in orange, only after a while they take on the green status. This is a normal symptom that consists in first of all in reading the MAC addresses of connected computers in a given segment.

Figure 5.27 Network bridge connecting two LAN segments To check the bridge configuration, you must generate some traffic from one network segment to another. Then you can use the Inspect tool , applied to the bridge, which you can click with the left mouse button, and then select MAC Table from the context menu, as shown in the figure below.

Figure 5.28 Selecting MAC Table

After that, a window will be displayed on the screen with an array of MAC addresses in the devices and the port number of the bridge to which they are attached.

Figure 5.29 Example array of MAC addresses in the bridge What happens when a test packet is sent from PC0 to the printer in simulation mode? The bridge will distribute packets to all devices, but when the bridge receives the MAC address of the recipient of the packet (that is, the printer) and checks that it is on the same (left) segment of the network, it passes the packet further (to the same collision domain), as shown in the figure below.

If the MAC address of the packet recipient is on a different (right) network segment, the bridge will pass the packet further (to another collision domain).

Figure 5.30 Limit the collision domain over the bridge

If the packet were addressed to any computer located in the right segment of the network, e.g. PC5, the bridge would simply pass the packet.

5.4 Switches

This section shows the basic network switches, also called switches, which can be used in the Cisco Packet Tracer. In the Cisco Packet Tracer we have a full range of them at our disposal. If you want to see the entire library of devices, select the Switches section from the bottom tray, and then all available switches appear on the right side, as shown in the figure below.

Figure 5.31 Network switch models available in the Cisco Packet Tracer In the program, the available devices can be divided into two categories: real devices used on a daily basis and virtual devices, which the user can freely modify. In real devices, components cannot be removed, added, or replaced. An example of this type of device is the basic Catalyst 2950 series 24-port switch, which is shown in the figure below.

Figure 5.32 Switch Catalyst 2950

The another next real device is also the basic 24-port Catalyst 2960 series switch.

Figure 5.33 Switch Catalyst 2960

Both of the above series of switches belong to the group of fully configurable devices with a built-in IOS system, but for a user who will not apply changes in the so-called "zero configuration" there will be no differences between this type of devices. The another next device in this group is the basic Catalyst 3560 series multilayer switch, which can work in two layers of the OSI model. Knowledge of the operation of this type of device will not be necessary in this part of the book. Detailed configuration of this type of switch requires advanced knowledge of computer networks.

Figure 5.34 Catalyst 3560 Series Multilayer Switch

In the Cisco Packet Tracer, there are two types of virtual devices (switches) that can be freely modified for the needs of the network. These are switches marked in the program as PT .

The one of them is the Switch-PT switch, which by default has 4 Fast Ethernet and 2 Fiber optic ports and 4 empty ports, which gives a total of 10 ports at the disposal of the PT user.

Figure 5.35 Switch-PT

The another one is the Switch-PT-Empty switch, which has 10 empty ports. It gives you the opportunity to equip with appropriate interfaces, in accordance with the previously learned rules.

Figure 5.36 Switch-PT-Empty

The example topology contains 6 network devices and two segments. Two Switch-PT-Empty switches were used. The topology should look like the following figure.

Figure 5.37 Example topology based on two network switches After going to the simulation and performing a connection test between the PC3 and the printer, the packet passing through Switch 1 , based on the physical MAC addresses of the end devices, will recognize the recipient and forward the packet only to the appropriate port, thus limiting excessive traffic.

In this situation, there are two independent network segments, during which each device together with a single switch port forms a single, small micro-segmentation of the LAN (micro-segmentation) called a collision domain .

Figure 5.38 Packet route using switch

Sometimes, when simulating in slightly more complex networks, a message may appear at the very end of the network informing about a buffer overflow, as shown in the figure below.

Figure 5.39 Overflowing list of events during simulation

Then press the Clear Event List button to clear the list of events and return to the simulation.

5.5 Access Points

If you want to make a network based on access points, i.e. wireless, you must use the appropriate devices, which are available in the Wireless Devices section. In this section there are 3 very similar devices that differ from each other in the frequency of work, and thus classes, e.g. A or N. If you want to make a network based on access points, i.e. wireless, you must use the appropriate devices, which are available in the Wireless Devices section. In this section there are 3 very similar devices that differ from each other in the frequency of work, and thus classes, e.g. A or N.

Figure 5.40 Types of wireless devices

The View of the Access-Point in the Cisco Packet Tracer is shown in the following figure. This is a typical device with one FastEthernet port, which of course can be exchanged for another network interface.

Figure 5.41 Physical view of the Access Point

You can build a network based on the same end devices as in the previous chapter, but often the role of switches and routers is taken over by access-points. However, creating such a topology will not be as easy as before. The first thing to do is to equip each computer with a wireless card. This action should not cause much difficulty, but when we put one Access Point in the workspace, the connections to it will be made automatically and when we put a second Access Point, there will probably be a problem that no end device wants to connect to the other access device. As is the case in the figure below .

Figure 5.42 Connected end devices with one Access-Point

There are two ways to resolve this issue, which you should look for in the configuration of access devices. After clicking on the right Access Point 2 device with the left mouse button (to which no computer has connected), you need to go to the Config tab. Two ports are configured:

 Port 0 – responsible for the wired link of the device,

 Port 1 – responsible for the wireless link.

In our case, you go to Port 1 where the WIFI network was encrypted, for example, we will use the WPA2 key, entering the password: cisco321 . After applying the changes, it will not change much in our topology, because you still have to manually connect computers to the encrypted WIFI network.

Figure 5.43 Fast Ethernet port configuration window in Access-Point

Figure 5.44 Wireless port configuration window in Access-Point Now you need to encrypt access to the second access point using WPA2-PSK encryption and the password " cisco321 ". You can connect selected computers to it by setting the same type of encryption on them and providing a password. To do this, click on PC5 with the left mouse button and go to the Config tab. Then, in the list of interfaces, search for the Wireless port in which in the Authentication section select WPA2-PSK encryption and enter the password: cisco321 in the Pass Phrase field.

Figure 5.45 Selecting encryption on your computer's wireless card After leaving the configuration window, after a while the connection will be made automatically. When all the computers in a given segment are connected, the topology should look as shown in the figure below.

Figure 5.46 Connected terminal equipment to the appropriate access points In order to connect access-points with each other, a patch cable in the FastEthernet standard should be used. Ultimately, the topology should take the following form.

Figure 5.47 Connection of two wireless LAN segments

The prepared network is already ready for simulation, assuming that Access Point 1 does not encrypt the signal, and Access Point 2 connects computers using WPA2 encryption. Due to the fact that you should not leave the Wi-Fi network open, but you should encrypt the signal, you could be tempted to set Access Point 1 to encrypt with a different key or type of encryption.

Figure 5.48 Disconnected network devices after changing wireless network settings in Access Point 1

In this case, there will be no signal encryption for simulation purposes, but you must intentionally rename the SSID so that the computers disconnect the automatic wireless connection, achieving the situation shown in the following figure. For the purposes of the exercise, the new SSID name is AP1 .

Figure 5.49 Setting the SSID on the Access Point

You need to manually connect each computer by clicking on it with the left mouse button and going to the Config tab to finally enter AP1 in the SSID field. When you close the window, the connection will be made automatically.

Figure 5.50 Setting the SSID on the computer's wireless card

5.6 Other Access Point Wireless Devices

5.6.1 LAP-PT Devices

The LAP-PT is part of the wireless access point group and is used only for Wi-Fi operations. You can configure static addresses, possibly dynamic via DHCP: gateway address, DNS address and radio signal access range in meters ( maximum 1000 m ).

Figure 5.51 View of the LAP-PT device available in the program The device has only one Gigabit Ethernet port and a built-in Dot11Radio module for radio communication.

5.6.2 3702i Device

The 3702i belongs to the group of wireless devices such as the Cisco Aironet access point controller.

It is used to operate the Wi-Fi network in which WLC controllers are located. You can configure the static address of the Wireless Controller (WLC). The following static or dynamic addresses can be configured for the internal network: gateway address, DNS address and radio signal access range in meters (maximum 1000 m). The more accurate operation and configuration of this device is beyond the scope of this book, and therefore these capabilities will not be described.

Figure 5.52 View of the 3702i available in the program

The device has only one Gigabit Ethernet port and a built-in Dot11Radio module for radio communication.

5.6.3 WLC-PT Device

The WLC-PT device belongs to the group of wireless devices such as the Wireless LAN Controller . It is used to operate the Wi-Fi network in which WLC controllers are located. You can configure a static address for the management interface called Management .

Figure 5.53 View of the WLC-PT available in the program The device has only one Gigabit Ethernet port (without the possibility of its configuration) and a built-in Dot11Radio module for radio communication. It is equipped with two ports:

 GigabitEthernet0

 Management

 Wireless LAN, AP Groups

The following static addresses can be configured for the internal network in the Management interface: IP address, subnet mask, default gateway address, DNS address. The Wireless LAN module allows you to configure, among others: type of authorization, RADIUS server configuration, encryption type. The AP Groups module allows you to configure, among others: LAN groups, SSID names belonging to groups. You can also freely configure the DHCP addressing pool on the device.

The more accurate operation and configuration of this device is beyond the scope of this book, and therefore these capabilities will not be described.

5.6.4 WLC-2504 Device

The WLC-2504 belongs to the group of wireless devices of the Access Point Controller type (the so-called Wireless LAN Controller ), in which only the Management interface can be configured.

Figure 5.54 View of the WLC-2504 available in the program The device is equipped with:

 1000 Mbps Gigabit Ethernet interfaces ( GigabitEthernet0-

GigabitEthernet3 )

 one Management interface where you can configure the following static addresses: IP address, subnet mask, default gateway address, DNS address.

More accurate operation and configuration of this device is beyond the scope of this book and therefore these capabilities will not be described.

5.7 Wi ‐ Fi Access Routers

The next device that we will present will be an access router, that is, a device containing 3 different functions:

 Switch

 access-point

 router

The Integrated Services Router in the Cisco Packet Tracer looks like the following figure.

Figure 5.55 Physical appearance of the access router in the Cisco Packet Tracer

5.7.1 Standard Configuration of the Wi-Fi Router

An example network is a LAN consisting of 3 computers, two of which are connected directly to the Wi-Fi router using a simple cable in Fast Ethernet technology, while the third computer is equipped with a Linksys WMP300N wireless network card (the use of this card will allow you to configure the router via the WWW later in this chapter). From the WAN side, a server or cloud emulating Internet behaviour is connected to the Wi-Fi router – connected to the WAN port. On the WAN side there is a Laptop, which is connected by a patch cable to the router. The described situation is illustrated in the figure below.

Figure 5.56 Connected devices to the access router

After making the necessary connections, you may notice that the computer connected wirelessly received an IP address automatically, while the computers connected by wire did not. Automatic wireless addressing is accomplished through the router's built-in DHCP service, which is responsible for assigning IP addresses to computers. In order for computers connected by wires to also receive IP addresses, it is necessary to change the STATIC option to DHCP in the IP Configuration section, on the Config tab and the Fast Ethernet port, for each computer.

Figure 5.57 Automatic setting

After some time, you will be able to see that in the IP Address and Subnet Mask fields for PC 1 and PC 2, the network parameters obtained from the router will appear. It should also be remembered that the second option to switch a computer to automatic acquisition of IP addresses is to use the tool available on the desktop of each computer, and this is the IP Configuration tab.

The result of the automatic operation (DHCP) of address assignment is described in the following figure.

Figure 5.58 Setting automatic IP address assignment

Another network parameter has been assigned by the router, not yet described, which is Default Gateway. Default Gateway , which is the IP address of the router as seen from the LAN side. It is not needed for communication between computers located on the same LAN subnet, but it will be required to communicate with a Laptop connected to the WAN port of the router. Checking whether all the necessary parameters have been obtained is also possible through the command line, using the ipconfig command.

Figure 5.59 Checking the received IP address by the computer In order to check the configuration of the WIFI router, click on it with the left mouse button and go to the Config tab, and then to the LAN section. In the LAN section, you can see the IP address of the router, which is also the IP address of the Default Gateway .

Figure 5.60 Router LAN Configuration

On the Config tab, in the Wireless section, you can configure the settings of wireless (internal) network parameters.

Figure 5.61 Router wireless network settings

On the Config tab, in the Internet section, you can configure the settings of WAN (external) network parameters.

A cloud that emulates Internet behavior has an IP address of 10.0.0.1 and a mask of

255.0.0.0. The laptop should be assigned the address 10.0.0.2 with the same network mask, since it is located on the external network Internet.

Figure 5.62 Router WAN Port Configuration

Execution of several simulations for transmission between LAN and WAN networks. The first simulation is an ICMP packet sent from a computer from the LAN and we send the ICMP packet from PC 3 to a laptop connected to the WAN port. The packet passes through the router, reaches the recipient, after which the response is transmitted. The answer comes to PC 3.

Figure 5.63 Transmission of ICMP packet from LAN to computer in WAN The situation is different if you reverse the direction of transmission and send a packet from a computer connected to the WAN interface to any computer in the LAN. The second simulation is an ICMP packet sent from a laptop from a WAN from Laptop to PC 3 or PC 2, or PC 1, connected to LAN ports.

In each access router, the default firewall of the local network works, thanks to which it will not pass such a packet further, and thus there will be no response to the ICMP (ping) packet formulated in this way. This situation is shown in the figure below.

Figure 5.64 Block a packet from WAN

5.7.2 Configuration of Wi-Fi Router via HTTP

The second way to configure a Wi-Fi access router is to configure using a website using a browser. By default, the router has an IP address from the LAN side: 192.168.0.1 . Simply connect to any port on your device and enter the router's IP address and start setting up. You must configure any address in the 192.168.0.0/24 pool on the computer, but different from the 192.168.0.1 address, for example, 192.168.0.2 and the subnet mask for this network class/24, which is 255.255.255.0. and the gateway 192.168.0.1 .

Figure 5.65 Enter the IP address of the router in the web browser window If your computer is not responding to an IP address, your computer's address is misconfigured, or the mask or gateway or network cable is incorrectly connected. Correctly entering the router's IP address in the browser window should result in the router login window appearing. With the default settings, the login and password are the same, i.e. you log in by providing the following parameters: admin , admin .

Figure 5.66 Logging in to your router

After logging in to the router, a window will appear, configuring the router, which is shown in the figure below. It should be remembered that in many network devices, configuration via the http protocol gives more convenient options in operation and many greater possibilities than via the command line (e.g. ASA 5506 devices).

Figure 5.67 Basic Router configuration options

First of all, pay attention in our topology whether the Static IP option is selected on the Setup-Basic Setup tab in the Internet Connection Type section. The most important options (data) to configure are:

 Internet Address (Internet IP Address and Subnet Mask) WAN

 Internal address ( IP Address and Subnet Mask ) LAN

 DHCP Server Settings

Figure 5.68 Selecting static WAN port addressing

In this example, you must manually set the IP address for the Internet (WAN) port to

10.0.0.1/8. Due to the fact that usually the access router from the WAN side connects to another router, you need to enter the IP address of the next device in the Default Gateway field, in this case it will be the IP address of the laptop connected to the Wi-Fi router (10.0.0.2). In the IP Router section, leave the default IP address of the router from the LAN side (i.e. for now we do not change the default parameters 192.168.0.1/24 ). Then, in the DHCP Server section, set the Enabled parameter to enable dynamic addressing of computers on the LAN side. An important element is to set the DHCP pool, i.e. from which number IP addresses will be assigned and how many computers will obtain network parameters. To do this, configure in the Start IP Address field (default

192.168.0.100), and in the Maximum number of Users section (50 by default). The final step to save your changes is to click the Save Settings button at the bottom of the window. After performing the above actions, the following window will appear, in which information about the correctness of saving changes is given.

Figure 5.69 Saved changes on the router

After making changes to the router settings, close the window. Computers should receive IP addresses. Also, it should be remembered that if any computer has not received network parameters, it is advisable to check whether it is enabled in DHCP mode or refresh the network parameters of computers when changing DHCP parameters. This can be done, for example, through the command line. Just type ipconfig /release (to release the IP address) and then ipconfig /renew (to renew), as shown in the figure below.

Figure 5.70 Release and renewal of the IP address via the command line A common problem when configuring a router from the LAN side is changing the default address pool. This is the case when, for example, we want our router to allocate addresses from the network (for example, 200.0.0.0 ). Then, we start by assigning an IP address to the router ( 200.0.0.1 ), as shown in the figure below, and the DHCP pool has remained unchanged and cannot be reconfigured in this step. In this case, first press the Save Settings button to save the changes on the router.

Figure 5.71 Saving router configuration changes

After saving the changes, you can observe that the browser window displays a message about the exceeded waiting time and the connection to the router has been interrupted, as the figure below illustrates. This is because the router already has a different IP address, so all computers connected to the LAN should refresh the IP address (if they receive it from DHCP) or enter manually from the new pool, for example 200.0.0.2/255.255.255.0 .

Figure 5.72 Interrupted connection to the router after changing the IP address After successfully reconnecting with the router, you should go to the second Wireless tab, where you can configure the Wi-Fi settings. The first section is Basic Wireless Settings in which you can change the network mode ( B, G, N ), the SSID name with which computers connect to the network or set the parameters whether the SSID is to be broadcast on the Wi-Fi network or not.

Figure 5.73 Basic Wi-Fi settings

The next section is Wireless Security , where you can set the network encryption type and password, for example, WPA2 Personal and sample password: cisco321 .

Figure 5.74 Wi-Fi security setting  

After saving the changes to the Wi-Fi router, you need to configure the computer(s) to connect it to the new network parameters. We can do this through the standard configuration of the computer, but in this example we will do it through the tool available on the computer's desktop.

Figure 5.75 Wi-Fi configuration tool via the desktop utility of the computer A prerequisite for connecting the computer to the Wi-Fi network through this tool is to install a LINKSYS wireless card in the computer. To start the configuration, run the IP Wireless utility shown in the figure above from the computer's desktop, and then the following window should open.

Figure 5.76 Tool for Wi-Fi configuration of computers equipped with the LINKSYS wireless card

Go to the second Connect tab, then press the Refresh button to display the available Wi-Fi networks, and then the Connect button to connect to it.

Figure 5.77 Connecting to the selected Wi-Fi network

After a while, another window will appear in which you need to select the encryption type and enter the appropriate password and press the Connect button again. When all the specified parameters meet the specified rules, a wireless connection will occur.

Figure 5.78 Choose encryption and enter your password (Pre-shared Key) Another tab of the Wireless section is the Wireless MAC Filter , where you can configure which computers connected via Wi-Fi will have access to the network and which will not. In order to better illustrate the issue, you should connect 3 additional computers to our local network, which are equipped with LINKSYS wireless cards. Computers should be properly configured to connect, as shown in the figure below.

Figure 5.79 Connected additional computers to Wi-Fi

Assume that you filter the list of computers that you want to have access to the network and that you do not. In this case, PC3 and PC4 will be connected, and PC5 and PC6 will not be connected. First, read the physical (MAC) addresses of the computers you want to access (PC3 and PC4). Here are three ways to obtain MAC addresses. The first way is to point the mouse cursor over the icon of a given computer and after a while a window will appear in which the physical address appears.

Figure 5.80 The first way to get your computer's MAC address The second way is to enter the configuration window of a given computer interface and in the MAC Address field, you can read the physical address.

Figure 5.81 The second way to get a physical address

The third way is to enter the previously known ipconfig /all command in the console window:

Figure 5.82 The third way to get a MAC address

Knowing the different ways to obtain MAC addresses, choose one of the ways and copy the MAC addresses of PC3 and PC4, then in the wireless MAC Filter router window, select Enabled .

Note: MAC addresses in presenting examples, which you see may be variable, because the Cisco Packet Tracer randomizes addresses . We use addresses as examples in this book only .

To allow the following computers: PC3 and PC4 to connect to the network, select the section: Permit PCs listed below to access wireless network and finally enter the physical addresses of the computers in the MAC 01 and MAC 02 fields.

Figure 5.83 MAC Address List

Then save the settings. To save your changes, click the Save Settings button at the bottom of the window.

Figure 5.84 Saving the Wi-Fi Router Configuration

Figure 5.85 MAC address filtering

As a result of the saved changes, the situation shown in the figure below was obtained, noting that pcs PC5 and PC6 lost connection to the WiFi network.

Figure 5.86 LAN after MAC address filtering

Note: After starting the Cisco Packet Tracer, MAC addresses may be different, so please update them on your router.

In addition, in the Security router tab, you can set parameters related to the Firewall and the ability to block or accept web scripts.

Figure 5.87 Firewall configuration on the router

By going to the Access Restrictions tab, you can configure a list (lists) according to which you can specify which computers can have access to specific applications, at what times, what websites and at what keywords will be blocked, as well as which port ranges will be allowed and which will not.

Figure 5.88 Configuring router access restrictions

In the Applications & Gaming tab in the Single Port Forwarding section, you can set options based on which the router will pass or block packets from specific network applications, directed to specific computers.

Figure 5.89 Packet filtering based on protocols and ports

On the same tab there is another section called DMZ , that is, the so-called Demilitarized Zone, in which most often there is a server or a group of servers that can be accessed from the WAN. In this section, you can specify the source address, the so-called trusted, and the destination address that you want to access from the WAN.

Figure 5.90 Configuring DMZ on the router

The next tab of the router is Administration , in which there is a Management section: it is recommended to change the default password: admin , to a new one, e.g. packettracer , after saving the changes you will be able to log in to the router with the following parameters: login: admin , password: packettracer . In addition to changing the password, you can also specify in this section what protocol will be used to be able to connect to the WIFI server ( HTTP or HTTPS ) and whether it will be possible to connect to the router remotely from the WAN.

Figure 5.91 Options of the Management tab in the router

On the same tab there is also a Factory Defaults section, where using the Restore Factory Defaults button, you can restore the router to factory settings.

Figure 5.92 Restore default settings

The third section in the Administration tab is Firmware Upgrade , where you can update the router's service software from a file saved on our computer. This option should be handled very carefully – if the device works properly, it is not recommended to update firmware.

To upgrade a firmware, press the Browse button to point to the firmware update file, then click Start to Upgrade and watch the update installation progress.

Figure 5.93 Router software update window

The last Status tab consists of three sections.

 Router Information

 Local Network

 Wireless Network

The first is Router Information , where you can see the basic data of the router and its LAN interface configuration.

Figure 5.94 Status tab and Router section

The next section is Local Network , where you can read data about the configuration of the router on the LAN side as well as information about the DHCP configuration.

Figure 5.95 Status tab and Local Network section

The last section is the Wireless Network , where you can check the configuration of the wireless network, encryption and the name of the broadcast SSID.

Figure 5.96 About Wi-Fi in the Wireless Network tab

5.8 Devices for Creating GSM Networks

In the Cisco Packet Tracer, the BTS base access station in a 3G/4G cellular network is simulated as a pair of two devices ( Cell-Tower and Central-Office-Server ) that must be connected to each other using a coaxial cable (the type of cable is Coaxial ).

Figure 5.97 Appearance of the real BTS (Base Transceiver Station) In the Cisco Packet Tracer, the BTS consists of an antenna (called as Cell-Tower ) and a dedicated server (called as Central-Office-Server ).

Cell-Tower acts as a sector antenna in the 3G/4G network for wireless connections. Central-Office-Server sets the default IP address for the cellular network and is responsible for communication with the WAN backbone.

Figure 5.98 BTS simulation in the program

An example of a simple 3G/4G network using Cell-Tower and Central-Office-Server is shown in the figure below.

Figure 5.99 Simulation of a simple 3G/4G network

5.9 Hardware Firewalls

5.9.1 Meraki-MX65W Device

The Meraki-MX65 is primarily designed to filter network traffic and isolate internal networks (LANs) from external networks (WANs).

Figure 5.100 View of meraki-MX65 available in the program The Meraki-MX65 comes standard with:

 2 x 1000 Mbps interfaces ( Internet1 , Internet2 ) for WAN connection

 8 x 1000 Mbps interfaces ( GigabitEthernet3 – GigabitEthernet10 ) for LAN connection

 2 x 10 Mbps or 100 Mbps interfaces ( Ethernet11 – Ethernet12 ) for LAN connection

5.9.2 Meraki-Server Device

The Meraki-Server is used to support Meraki-MX65 authentication using advanced procedures, accounts, passwords, and advanced network security techniques, as well as the Meraki-MX65 serial number.

The Meraki-Server comes standard with one 1000 Mbps interface ( FastEthernet0 ). The description of the interaction of these devices is very complicated and therefore will not be described in this book.

Figure 5.101  View of the Meraki-Server device available in the program

Figure 5.102 Example of topology for Meraki devices

5.9.3 ASA5505 and ASA5506 Devices

The Cisco Packet Tracer supports two so-called Adaptive Security Appliances (ASA): ASA 5505 and ASA 5506 , which act as advanced firewalls. In the Cisco Packet Tracer, in the [Network Devices] [Security] section, you can find Security Appliances (that is, advanced firewalls). Two devices are available: ASA5505 and ASA5506-X .

Figure 5.103 Firewall devices available in the program

ASA devices are characterized by the following capabilities:

 IP packet filtering using ACL.

 Stateful filtering, i.e., the decision to pass or block a packet, is made based on port numbers and trust level.

 Act as a DHCP server or client.

 Support for static and dynamic address translation (static NAT, dynamic NAT, PAT).

 Support for dynamic routing protocols: RIP, EIGRP, OSPF and static routes.

 Define a group of objects that define a set of security (access) policies for greater configuration transparency.

 Support for Site-to-Site VPN tunnels.

 Supporting the AAA mechanism (authentication, authorization, settlement).

5.9.3.1 ASA 5505 Device

Figure 5.104 Appearance of the Cisco ASA 5505 front panel

Figure 5.105 Appearance of the Cisco ASA 5505 rear panel

5.9.3.2 ASA 5506 Device

Figure 5.106 Appearance of the Cisco ASA 5506 front panel

Figure 5.107 Appearance of the Cisco ASA 5506 rear panel

6 Basics of Data Transmission and Overview of Network Services

6.1 Transmission Types

This section discusses two types of transmission and how network devices behave when operating in a given mode.

6.1.1 Half Duplex

Half Duplex is a transmission during which data can run in both directions on one link, but not at the same time. The following network topology was used to analyse this issue, in which the connections between the two switches were configured in Half Duplex m od e .

Figure 6.1 Half Duplex link between two switches

Until now, when creating a LAN, the automatic link speed and link type mode was used. If you want to change the default settings, you must first check which port number of the switch corresponds to the connection, and then make the appropriate settings. After reading the port number (in our case: Fa2/1 on the left switch and Fa0/1 on the right), click the left mouse button on the switch icon. Then go to the Config tab and select the port number.

Next, on the Switch 1 switch, change the transmission type from Auto to HALFDUPLEX , as shown in the figure below. Similarly, perform the same action for the corresponding port on the right switch. On the Switch 2 switch, change the transmission type from Auto to HALFDUPLEX.

Basics of Data Transmission and Overview of Network Services

Figure 6.2 Setting the switch port to HALF DUPLEX mode You can now observe the operation of the network in this mode, for this purpose you should switch to Simulation mode, and then send two test packets at the same time from the left segment of the network to the right and vice versa.

Figure 6.3 Collision on the HALF DUPLEX link

Both packets try to traverse the section of the link between the two switches, a collision occurs, as shown in the figure above. Then the transmission is resumed by the network devices, but in such a way that the right switch generates packets, and through the HALF DUPLEX link it will pass only one of them when the packet reaches the target.

Figure 3.6.4 Packet caching by switch to avoid re-collision

6.1.2 Full Duplex

FULL DUPLEX transmission is definitely better (more modern), because it provides simultaneous movement through transmission media in both directions. If you want to test this transmission mode, you can use the same example as in the HALF DUPLEX transmission. Only in the configuration of the switch on the appropriate ports, set the FULL DUPLEX mode and proceed to the simulation. As you can see in the figure below, the simulation confirmed our theoretical expectations.

Figure 6.5 Full Duplex transmission on the link between switches

6.2 Configuring Network Services

This chapter describes the configurations of basic network services and protocols. Note – Warning: Remember to periodically save the file state (keyboard shortcut CTRL+S) during exercises.

6.2.1 DHCP

This section describes the DHCP service that is configured on the server. The following topology has been prepared for this purpose:

Figure 6.6 LAN with DHCP server

If you want to find a server among many devices, you should find it in the End Devices group, it is a device with the Server-PT name . The physical view of the device shows the following figure, which shows that by default one network adapter is installed on the server, with the possibility of attaching another.

Figure 6.7 Physical view of the server

The topology is already prepared and includes a DHCP server. When you left-click on the server icon, you will see its physical appearance with the installed components. Now you will need the available services, so go to the Services tab.

Figure 6.8 Window with configurable server services

Before you start configuring the DHCP service, it is necessary to give our server a static IP address so that it is located on the same LAN. Of course, as in the case of PCs, this is done in an almost identical way, using two methods:

 using the Config -> FastEthernet0 tab

 using the IP Configuration tool available on the server desktop, We assume that each of us can do this action on our own, hence we will not describe it in detail, but enter the IP address for our server: 150.150.0.1/16 .

At this point, the server has been prepared to configure the DHCP service. The first step will be to enter the configuration and select the DHCP section, then the service will have to be enabled by selecting On in the Service section. Because different address pools can be stored on the server, you can assign different names to them. In this example, one is enough, so leave the Pool Name field unchanged. An important element is to set the parameter from which IP addresses are to be assigned, i.e. Start IP Address , in the described case it will be 150.150.0.10 with the same network mask as the server. It is still worth configuring the maximum number of computers, in this example it is enough to set it to 10 . The most important, and at the same time the last configuration step, is to save the settings, which should be done by pressing the Save button. Basics of Data Transmission and Overview of Network Services

Figure 6.9 Configuring DHCP on the Server

All computers should be switched from static to dynamic addressing, after which they should receive an IP address, or you can refresh the IP address using one of the ways described in the previous chapters. After checking the addressing of the entire LAN, you can of course simulate the network to confirm the theoretical assumptions.

Figure 6.10 Obtained IP address from DHCP server via Laptop The DHCP server does not necessarily need to be configured on the server, it is possible to configure it on the router, and this will be described later in the chapter on configuring routers using the console environment.

6.2.2 HTTP

Another service that will be described in this chapter is HTTP. Of course, you could place subsequent network services on one server, but we will allow ourselves to place each of them on a separate device. Therefore, you need to add another server to the topology that you will connect to the network and configure it according to the adopted address: 150.150.0.2/255.255.0.0 .

Figure 6.11 Attaching an HTTP server to the LAN

After completing the described steps, you can now take care of the HTTP configuration. To do this, left-click on the server icon and go to the Services tab, and then click on HTTP . The first thing to do is to make sure that the service is enabled, there are two options http and HTTPS. Note that the main file that will display the contents of the HTML code must be named index.html , otherwise you will not be able to view the web page. When you click on [edit] next to the index.html file name, a window opens in which the default code that contains the sample page is entered, along with two subpages with references. The rest of the files in this [File Manager] tab are files used by the HTML page. By the way, it is also worth informing advanced readers that the HTTP server in the Cisco Packet Tracer also supports CSS files and Java Scripts .

Basics of Data Transmission and Overview of Network Services

Figure 6.12 http Configuration

In fact, for starters, it's all to be able to display the content of a web page on any LAN computer. To do this, through any computer, go to its desktop, and then using a web browser enter the address of the web page, in this example it will be the IP address of the HTTP server ( 150.150.0.2 ).

Figure 6.13 Type the HTTP server address

After pressing the Go button, the http page will be loaded.

Figure 6.14 Contents of a sample web page displayed in your computer's browser Of course, keep in mind that the default HTML code can be freely changed and modified. As a result of the changes, the sample page may look as shown in the figure below.

Figure 6.15 My Own website

6.2.3 FTP

Similarly to the previous cases, you can add an additional server on which to configure another FTP service. After adding another device, our LAN should already contain 3 servers. An FTP server is a file server. It allows us to download files from it and send files to it. We often deal with such servers on a daily basis – even by downloading a file from a platform.

Figure 6.16 Adding an FTP server to the network

Then you need to go to the configuration of the service, which, of course, can be found in the Services section. At the very beginning, you should ensure that the service is enabled, then in the User Setup section, define access parameters (usernames and passwords). Below you can specify the access rights to files from the FTP level, while at the very bottom of the configuration window there are sample file names that can be downloaded from the server.

Basics of Data Transmission and Overview of Network Services

Figure 6.17 FTP configuration

Now you can add two new users, it will be user1 with password 111 and user2 with password 222 . Different access rights will be defined for each of them, for example, the first user will only be able to view the contents of the server and download files, while the second user will be able to additionally rename files and upload their files to the server.

Figure 6.18 Defined FTP access rights for new users

File access rights on the FTP server:

 L – display of content (list of file names)

 R – reading files

 W – saving files

 D – deleting files

 R – renaming files

If you want to access the FTP server now, open a command line on any computer on the LAN and type ftp 150.150.150.3 (the IP address matches the server address).

Figure 6.19 Connect to an FTP server using the command line When you press Enter, you will be asked for your username and password. We must bear in mind that when entering a password, the characters that will be typed do not appear in the window, because for security purposes they are hidden, as shown in the figure below. When you connect to the server, you should see a message that you are connected to the service, and then the prompt from PC> to FTP> will be changed.

Figure 6.20 Log in to an FTP server

To find out what commands are available in this mode, you need to run a help command, or help .

Figure 6.21 View help in FTP mode

Common commands on an FTP server are:

 cd (change directory) – change the current directory in the server

 delete – delete the file from the server

 dir (directory) – display the contents of the current directory on the server

 get – download the file from the server

 put – send the file to the server

 pwd (print working directory) – display the name of the current directory on the server

 rename – rename a file on the server

 quit – log out of the server

The next step will be to display the available files that are on the server, for this purpose the dir command will be used. There should be a fairly long list of files available for download. Why do they have such long and strange names? Well, these are images of the IOS system of routers that we will use when working with professional routers. Therefore, at this stage of our adventure with the Cisco Packet Tracer program, we have to accept it and work on this type of files.

Figure 6.22 List of available files on the FTP server

If our permissions allow it, we can now download one of the files by typing the get command and after the space entering the full name of the file. In order not to be discouraged by typing long file names, we can select any of them with the mouse, copy and paste, but it should be remembered that the entire operation of copying the name should be done with the mouse, because keyboard shortcuts do not work.

Figure 3.6.23 Download a sample file from an FTP server

When the file is downloaded, the message File transfer in progress... is displayed, which means that this process is in progress. When the process is complete, another message will appear: Transfer complete , which informs you that the file has been downloaded correctly.

We will now try to present some other commands and permissions that we have assigned to the user on the server, which is why we will now try to delete the file using the delete command, as the figure below illustrates.

Basics of Data Transmission and Overview of Network Services Figure 6.24 Failed attempt to delete a file from an FTP server The console window displays information that the requested file does not exist or we do not have sufficient permissions. Since we are sure that we have entered the file name correctly, we are 100% sure that we do not have permission to delete it. Our user user1 can only view files on the server and download them, so now you need to log in to the second user user2 , who admittedly can not delete files but can change names. To do this, type quit to disconnect from the server and ftp 150.150.0.3 again and log in as user2 .

Figure 6.25 Rename a file on an ftp server

Then, after logging in correctly, type the command rename asa842-k8.bin aaa.com and after a while a message will be displayed informing about the correctly performed action. However, in order to see the effect of our actions, we list the files on the server using the dir command to finally check whether the file already has a new name, as shown in the previous figure.

We could now describe all the possibilities related to permissions, but we will leave it to the reader for his own exercises because it is done in the same way by using subsequent commands and defining the appropriate permissions.

6.2.4 SMTP/POP3

Once we have learned how to configure several well-known network services, the time has come for e-mail, so as in previous cases, we should add another server to our network, which will act as a server sending and receiving mail. The server address is:

150.150.0.4/255.255.0.0 . We will also choose two computers from the network that will send and receive (correspond) mail to each other. These will be PC1 and PC2.

Figure 6.26 LAN with email server

After the correct IP configuration, you can go to the settings necessary for the proper operation of email. In the Services tab of the server settings, find the Email section where you need to enable both services: SMTP Service and POP3 Service, responsible for sending and receiving mail.

We will set up two mail accounts:

Figure 6.27 Email configuration data

Basics of Data Transmission and Overview of Network Services

Figure 6.28 EMAIL Server Configuration

Next, we specify the domain name to type in the Domain Name : field, in this example we should type: Itstart.pl . Then we will create accounts of two users and assign them passwords. After the correct creation of user accounts, you can proceed to the configuration of mail clients, on those computers that will correspond with each other. To do this, on the selected computer, on the desktop, you need to left-click on the icon, which is shown in the figure below.

Figure 6.29 Email client icon, available on your computer's desktop The first time you start the mail client, the mail configuration window opens automatically. In the Your Name : field, you can type any name that appears on the recipient's computer, in the Email Address field, type the email address, in this example it will be: marco@itstart.pl . In the Incoming and Outgoing Mail Server fields, and type the mail server address 150.150.0.4 . Finally, in the Fields User Name : and Password :, we enter the username and password that was assigned to the user directly on the server. After entering all the parameters, save the settings by pressing the Save button.

Figure 6.30 Mail client configuration on PC1

Figure 6.31 Mail client configuration on PC2

After saving the settings, the mail client window will automatically open in which you can compose, send and receive messages.

However, before we compose the first email, close this window and configure the e-mail program on the second computer so that you can carry out full correspondence between them.

The first message is edited by pressing the Compose button, after which the editor opens, in which we will be able to edit the first e-mail. Field To : is responsible for entering the recipient, Subject : entering the subject of the e-mail and at the bottom in the empty field enter the content.

Figure 6.32 Compose and send a new message to George

The status of the sent message can be checked in the lower part of the window, where the following message should be displayed, informing about the correct sending of the e-mail.

Figure 6.33 The status of the sent message displayed

Now, we can enable the e-mail program on the second, configured computer. Press the Receive button to check incoming messages. After a while, the header of the received email should appear in the window.

Figure 6.34 Received email

Now all that remains is to respond to the received e-mail, to do this we click on the Reply button. Then we respond to the received letter and press Send again. The message should be delivered to the sender's computer.

Figure 6.35 Reply to an email you receive

6.2.5 DNS

When most of the services have already been discussed, there is one more thing left - DNS. We deliberately left this service at the very end to be able to show its impact on the use of the network and other well-known services using the DNS ( Domain Name System ) protocol. According to the previously adopted principle, we add another server to our network, which we address: 150.150.0.5/255.255.0.0 .

Figure 6.36 LAN after adding a DNS server

On the Server Services tab, select DNS and then configure it. First, the service must be enabled ( DNS Service On ). Then we add the names and addresses of the servers that we want to access through the names we provide, not by the IP address. Examples of addresses are shown in the figure.

Figure 6.37 DNS Server Configuration

From the server's point of view, the configuration is complete, but the service will not work properly until each computer on the LAN is configured correctly. Because the DHCP server allocates addresses in our network, it does not yet pass the DNS server address to all computers, as shown in the figure below. Of course, you could enter the DNS address for each computer manually, but we will show you how this process can be automated.

Figure 6.38 No DNS information on each LAN computer

So let's go to the DHCP server configuration, in which in the DNS Server field enter its IP address, and then in order to save the changes, click on Save .

Figure 6.39 Append the DNS server address to the DHCP server settings After performing the above steps, we refresh, by any means, the IP addresses of all computers and after a while they should receive information about the address of the DNS server, as shown in the figure below.

Figure 6.40 Received DNS server address

It would now be necessary to check whether DNS is working properly. First, test this by using the PING command on the command line of any computer. After you run Command Prompt, type ping www.post.pl . A positive response from the IP address 150.150.0.4 indicates that DNS is working correctly.

Figure 6.41 Verifying DNS operation via PING

The second option will be to enter the website via a browser using not the IP address but the name of the page. In our example, this will be typing the phrase: www.itstart.com

Figure 6.42 Correctly displayed web page, called by name

In a similar way, you can also check the operation of FTP services. Noteworthy, however, is the testing of mail. However, in the first place, the settings of each mail client must be changed. We delete the IP addresses in the Incoming and Outgoing Mail Server fields and enter the name of the mail server there, the same as entered in the record No. 2 in the DNS server.

Figure 6.43 Typing the name of the incoming and outgoing server Now all you have to do is compose a new message and send it. At the bottom of the window, a message will be displayed in which you will see information about the correct sending of the message, using not the IP address of the mail servers, but the names. Basics of Data Transmission and Overview of Network Services

Figure 6.44 Message about correctly sent mail

6.2.6 Firewall

Very often we deal with networks, with FIREWALLS, i.e. firewalls. Firewalls protect us either from unauthorized Internet traffic or from the possibility of potential intrusion on the server. In our example topology, we used four computers connected via a switch to a server running two HTTP and FTP services. By default, all devices (computers) can use these services. However, we will try to show how the FIREWALL on the server works and protects against unauthorized access from two computers. Our assumption will be to configure the server in such a way that a computer with an IP address : 10.0.0.2 does not have access to the HTTP service, while a computer with an address of 10.0.0.4 does not have access to the FTP service. Other computers can use all services.

Figure 6.45 Topology to configure FIREWALL on the serve First, go to the server settings, then to its desktop and find the FIREWALL tool, as shown in the figure below.

Figure 6.46 Enable the FIREWALL tool on the server

When you run the FIREWALL tool, the following window appears, in which you must first enable the service by switching the On/Off button to the On position in the Services field, as shown in the figure below.

Figure 6.47 Enable the FIREWALL service on the server

Now you need to configure rules on the server that will cause the aforementioned filtration of network traffic. In the Action field, you can select two options: Allow or Deny . Basics of Data Transmission and Overview of Network Services

Figure 6.48 Action field: Allow and Deny

The next important field to configure the FIREWALL service is to determine for which protocol the defined rules will work. In this field, you can select one in several protocols:: IP, ICMP, TCP, UDP.

Figure 6.49 Protocols for which we want to define FIREWALL rules IP addresses and inverted masks (so-called WILDCARD MASKS) remained to be configured, as well as port numbers intended to block or pass traffic, as shown in the next figure.

Figure 6.50 IP addresses and Wildcard Mask to define rules

So let's start with the initial assumptions we made at the beginning in this chapter. We define the first rule, for a computer 10.0.0.2, which we want to block from visiting a website located on the server with the address 10.0.0.1. To do this, in the Action field, select: Deny , then TCP protocol, specifying Remote IP , in which we type: 10.0.0.2 and Remote Wildcard mask : 0.0.0.0 (which is equivalent to the operation of the rule for only one computer as in the case of the /32 mask). Next, we need to determine from which ports it will not be possible to enter the server page: Remote Port : ANY (i.e. all) and which destination port to block: Local Port : 80 (because it is on this port that the HTTP service runs). Then we press the Add button to apply the rule. The full configuration of the first rule is shown in the figure below.

Figure 6.51 First Rule Configuration View

Now let's try from a computer with an IP address: 10.0.0.2, to enter the server's website. Open a web browser on the locked computer and enter the address 10.0.0.1 in it, which is the equivalent of the server's website. After a while, we receive the message: Request Timeout, which proves the correctness of the rule.

Figure 6.52 Web page not displayed due to the introduced FIREWALL rules Now let's check if the same computer can send a typical PING to the server. As the figure below shows, PING does not occur, which indicates that the FIREWALL rules are not yet complete.

Basics of Data Transmission and Overview of Network Services

Figure 6.53 No response to PING after the applied FIREWALL rule To restore the remaining traffic on PC1, go back to the server, to the FIREWALL tool, where you must now allow full IP traffic. To do this, we add a second rule according to the guidelines shown in the figure below:

Figure 6.54 Apply an IP permission policy

After doing this, we open the command line on PC1 and try to send the PING to the server again, which this time is a complete success, as the figure below shows.

Figure 6.55 Response to PING after applying the FIREWALL rule However, if we continue to try to open the page at 10.0.0.1 through the browser, it will end in failure, which confirms our assumptions.

Now we will define the next FIREWALL rule for PC3 with the IP address: 10.0.0.4. You want this computer to be denied access to the FTP service. As in the previous way, we define a prohibitive rule, as shown in the figure below. However, we must bear in mind that after its introduction, another rule must be added that will allow this computer to move in the IP protocol, as was the case with PC1.

Figure 6.56 FIREWALL rule prohibiting ftp service

Let’s check the operation of the rule: On PC3, open the command line and try to connect to the FTP server. Of course, this ends in failure, which once again confirms our assumptions.

Basics of Data Transmission and Overview of Network Services

Figure 6.57 No PC3 connectivity with FTP, after entering the FIREWALL rule To be sure, let's check whether PC1, which was supposed to be blocked from accessing only the HTTP service, can connect to the same FTP, which PC3 could not. As you can see in the next figure, PC1 does not have the slightest problems with connectivity to the FTP server.

Figure 6.58 Correct connectivity of PC1 to the FTP server, after entering firewall rules

If we were to check the operation of the other computers that are not covered by any rules, it would turn out that none of them communicates with the server: (does not respond to PING and does not connect to any of the services). This does not indicate an error, but the lack of introducing additional but at the same time final rules on the FIREWALL for other computers.

This can be done in two ways. The first way is to add a separate rule for each of the other PCs (PC2, PC3, PC4) that allows the use of the IP protocol. However, it would be very inconvenient to define separate rules for each PC in large LANs. Therefore, we will also show a method that will allow this action to be implemented into one rule. When creating entry data, we do not always have to refer to only one host, providing its unique IP address and typing 0.0.0.0 in the Remote Wildcard Mask field. Instead of a given IP address of the computer, we can enter the IP address of the network and in the Remote Wildcard Mask field specify for how many bits of the IP address the rule should apply. In this case, it is enough to enter the network address: 10.0.0.0 in the remote IP field and enter 0.255.255.255 in the Remote Wildcard Mask field, as shown in the figure below.

At this point, the remaining computers that were not covered by any FIREWALL rules so far were allowed full and unlimited network traffic.

Figure 6.59 FIREWALL rule for a group of computers on a LAN

7 Skill Exercises – Part I

This chapter contains simple exercises designed for novice users, in order to consolidate the acquired theoretical and to check Your skills.

7.1 Device ‐ To ‐ Device Connections

7.1.1 Connection of Devices According to the Scheme

Connect the devices together according to the diagram shown in the figure below. On some devices, you need to install new modules, because by default they are not built-in.

Figure 7.1 Exercise – Scheme Exercise 7.1.1.pkt

Solution:

 Check the installed network hardware on computers and switches.

 After finding that there are no modules on the switches, install two Fast Ethernet cards (1 for each computer) and one Fiber Fast Ethernet module for the connection between the switches.

 Make calls.

 Address computers (e.g. PC1:192.168.0.1/24, PC2:192.168.0.2/24)

 Perform a connection test with any tool (PING, simulation, etc.)

7.1.2 Connecting Devices to the Wi-Fi Router and Access Point Connect laptops to a Wi-Fi router using a wireless medium and connect computers to Access-Point. There is to be a physical connection between the Access-Point and the Wi-Fi router. In Access Point for SSID is to be set on PC , and in router on Laptop .

Figure 7.2 Exercise – Assumptions – Scheme Exercise 7.1.2.pkt Solution:

 Check the type of network adapters installed in your computers.

 Replace the installed network adapters with the Linksys-WPC300N (wireless) adapters.

 Set the SSID parameter on the PC to the Access-Point and the Laptop parameter on the router.

 Set the same settings on computers and laptops respectively.

 Connect the Access-Point to the Wireless Router using a simple cable (to Ethernet port 1).

 On PC1 and PC2, set IP addresses from the same address pool from which laptops got the address dynamically.

 Perform a connection test with any tool (PING, simulation, etc.)

Figure 7.3 Exercise – Solution – Scheme Exercise 7.1.2.pkt

7.1.3 Connecting Computers That Are At Longer Distance Then 100 Meters Connect computers that are separated from each other at a distance of about 225m - 280m , in such a way that the signal strength is sufficient to carry out the transmission. Due to the low investment outlays, this should be done in an optimal way. It is also not possible to open the device cases, and thus it is not possible to make changes to the current network adapters.

Figure 7.4 Exercise – Exercise 7.1.3-Assumptions.pkt

Figure 7.5 Exercise – Exercise 7.1.3-Assumptions.pkt

Solution:

 Check the type of network adapters installed in both computers (Ethernet adapters).

 According to the assumption of network standards in this standard, the maximum cable length is 100 m – so use repeaters.

 Use 2 repeaters.

 Connect the devices with appropriate wires – computers with repeaters using a simple cable, and the connection between repeaters with a patch cable.

 Address computers (e.g. PC1 – 172.16.0.1/24, PC2 – 172.16.0.2/24)

 Perform a connection test with any tool (PING, simulation, etc.)

Figure 7.6 Exercise – Exercise 7.1.3-Solution.pkt

7.1.4 Using a HUB to Connect Devices Into a Single Local Network Connect 5 computers into one LAN in such a way that all devices are in one network segment. Due to technical conditions, hardware changes cannot be made to computers. Be sure to use the simplest solution when doing the exercise.

Figure 7.7 Exercise - The technical objectives - Scheme 7.1.4 Solution:

 Check the type of network adapters installed on all computers (a Fiber Gigabit Ethernet network adapter should be installed on PC4 and PC5 to make the task more difficult).

 Install the appropriate ports in the hub that are compatible with the network adapters of the computers.

 Connect devices to each other with cables.

 Address the devices so that they are all on the 10.0.0.0/8 network.

 Perform a connection test with any tool (PING, simulation, etc.)

Figure 7.8 Exercise – Solution – Scheme Exercise 7.1.4.pkt

7.1.5 Using a Bridge to Limit Packet Collisions on a Local Network In the local network shown in the figure, there are often packet collisions that we definitely do not want. To fix this, use a device called a bridge that divides the network into two collision domains.

Figure 7.9 Exercise - The technical objectives

Solution:

 Search for a bridge in the device bar and insert it in the middle of the network – between two HUBs.

 Wait for the network to synchronize.

 Address devices so that they are on the 192.168.0.0/24 network

 Perform a connection test so that two devices simultaneously try to communicate with each other from two different parts of the network .

Figure 7.10 Exercise – Solution – Scheme Exercise 7.1.5.pkt

7.2 Configure Services on Servers

7.2.1 DNS and HTTP Configuration

You have to create a LAN working with two desktop computers and two servers connected to the switch. One server will serve as a DNS server with a www.lan.xyz entry that corresponds to the IP address of the other HTTP server. The addressing of this network is based on the address 20.0.0.0/24.

Figure 7.11 Exercise – The technical objectives – Scheme Exercise 7.2.1.pkt

Solution:

 Address the devices so that they are all on the 20.0.0.0/24 network.

 Configure the HTTP server by removing unnecessary files from the HTTP service and leaving index.html. In the finished index, change the HTML code so that your name and surname are displayed.

 Configure the DNS server so that dns contains an HTTP server entry under the name www.lan.xyz.

 Perform a DNS and HTTP test from one of the computers by typing the www.lan.xyz address in the browser.

Figure 7.12 Exercise – Solution – www.lan.xyz - Exercise 7.2.1.pkt

7.2.2 Configuring DHCP and FTP

In this case, you have to create a network in which all end devices get addresses dynamically from the pool on the DHCP server (the address pool starts with 172.16.0.10, in the network 172.16.0.0/24) and have access to FTP server resources (address

172.16.0.1) by authorizing themselves as user1 with the password zaq1@WSX .

Figure 7.13 Exercise – The technical objectives

Solution:

 Address both servers statically (FTP server – 172.16.0.1/32, DHCP server –

172.16.0.2/32)

 Configure address pools on the DHCP server, which is available to a maximum of three users and starts at 172.16.0.10/24.

 On the FTP server, create user1 with the password zaq1@WSX .

 Enable dynamic IP address on each of the three devices.

 Log in to the FTP server from your Laptop .

Figure 7.14 Exercise - Solution – part one

Figure 7.15 Exercise - Solution – part two

7.2.3 Mail Server Configuration (SMTP, POP3)

There are two laptops in the exercise – one is the Boss and the other is the Employee . They use the email.com server as their mail server. The domain name on the server is the same as its name, and the users are the names of the laptops (passwords the same). You have to configure the devices in such a way that both laptops can communicate with each other via mail. Finally, send an email called TEST from one to the other.

Figure 7.16 Exercise – The technical objectives – Scheme Exercise 7.2.3.pkt

Figure 7.17 Exercise – Email configuration – Scheme Exercise 7.2.3.pkt Solution:

 Address all devices in the right way.

 On the mail server, configure the domain name and two users.

 On both laptops, set the mail service based on device names and setting

192.168.0.1 as the mail address.

 Send an email with the title TEST from one laptop to another.

Figure 7.18 Exercise – sending e-mail

Figure 7.19 Exercise – receiving e-mail

8 Configuring Cisco Routers

This chapter covers the basic theoretical and practical knowledge of configuring simulated routers in the Cisco Packet Tracer.

8.1 Exploring the Equipment of Cisco Routers At the beginning we will focus on the basic models of routers and their equipment that we will be able to install in them. We have twelve different types of routers from 829 to 4321 series. In addition to the standard routers, there are two more called PT-Router and PT-Empty , which can be modelled and reconfigured in any way.

Figure 8.1 Router models available in the Cisco Packet Tracer Routers available in the program are equivalents of real models encountered in everyday life, they differ not only in physical appearance, but also in software, as well as equipment. Below we will discuss the most important types of routers available.

8.1.1 Series 1841

The first router, we will describe is the 1841 series router, usually dedicated to small and medium-sized businesses, in the CISCO IOS 12.4 software version. By default, it is equipped with two Fast Ethernet ports with a bandwidth of 10/100Mbps and two free WIC/HWIC slots for installing expansion cards.

Figure 8.2 Physical Appearance of Router 1841

The router has two free slots, to which it will be possible in the future to mount the following compatible modules:

 Configuring Cisco Routers

Figure 8.3 Router 1841 Optional Equipment

Below are the detailed parameters of the optional equipment of the 1841 series router:

 HWIC-1GE-SFP – High-bandwidth network

adapter for WAN connections,

 HWIC-2T - 2 serial interfaces for high-speed

 HWIC-4ESW - 4 switch interfaces,

 HWIC-8A - interface enabling connection of up

to eight console connections in the EIA-232 standard,

 HWIC-AP-AG-B - wireless interface,

supporting single (802.11b/g) and dual-band (802.11a/b/g) bands,

 WIC-1AM - 2 interfaces used for basic telephone

service connections. One port can be used to connect to a standard telephone line, and the other to a regular analogue phone,

 Configuring Cisco Routers

bandwidth of 10Mbps for connecting LAN in the 10BASE-T standard,

 WIC-1T - single serial port used for connections

of remote locations or legacy network devices: SDLC hubs, alarm systems and devices operating via SONET,

 WIC-2AM - two RJ-11 connectors used for basic

telephone service connections, equipped with modem ports that can provide connections of various data,

 WIC-2T - Intelligent serial connector supporting

a wide range of interfaces when using suitable transition cables. It can support various protocols such as: PPP, Frame Relay,

 WIC-Cover -    a cap to protect the router's internal

electronic components and to ensure adequate airflow during cooling.

 GLC-LH-SMD - allows you to set up a Gigabit Ethernet connection using single-mode fiber.

8.1.2 Series 1941

Another router available in the program is the 1941 series router, which, like its predecessor, is dedicated to small and medium-sized businesses, but has two gigabit Ethernet cards with a bandwidth of 1Gbps and IOS software version 15.1.

Figure 8.4 Physical appearance of the 1941 route

It has two free slots to which you can mount optional equipment, which is no longer as diverse as in the case of the 1841 series.

 Configuring Cisco Routers

Figure 8.5 Optional Equipment for Router 1941

Due to the fact that the equipment coincides with the 1841 version, and is even much poorer, we will not describe it again.

8.1.3 Series 2620XM

Another router available in the program is the 2620XM series router, by default equipped with one Fast Ethernet port with a bandwidth of 10/100 Mbps. In addition, it has 3 free slots, to which you will be able to install very rich equipment.

Figure 8.6 Physical Appearance of the 2620XM Router

Unlike the 1800/1900 series, this type of router, in addition to two WIC/HWIC slots, can be additionally equipped with NM cards, which significantly expand its capabilities:

 Configuring Cisco Routers

Figure 8.7 Optional equipment for the 2620XM

 NM-1E - a single Ethernet port that can be

used for both LAN applications and can support up to six PRI ISDN lines or 24

 NM-1E2W - a single Ethernet port with the

same application as the NM-1E, with the difference that it has two additional

 NM-1FE-FX - single Fast Ethernet port in

 NM-1FE-TX - single Fast Ethernet port for

use in typical LANs and VLANs.

 Configuring Cisco Routers

with the same application as the NM-1FE-TX with the difference that it has two

 NM-2E2W - two Ethernet ports with two

 NM-2FE2W - two Fast Ethernet ports and

 NM-2W – two WIC slots.

 NM-4A/S - four asynchronous/synchronous

serial modules. Each port can be configured individually in any synchronous or

 NM-4E - 4 Ethernet ports.

 NM-8A/S - eight asynchronous/synchronous

 NM-8AM – network module providing 8

ports for low-bandwidth analogue telephone lines. The standard of the module sockets is RJ-11, dedicated to connections of integrated analogue modems of telephone lines operating on the public telephone network (PSTN) or private

 NM-Cover .

The remaining WIC ports were already described in the case of the equipment of the 1841 router .

8.1.4 Series 2621XM

Another router available in the program is the 2621XM series router. By default, it is equipped with two Fast Ethernet ports with a bandwidth of 10/100 Mbps, It also has 3 free slots in which you can mount optional equipment. In principle, this router differs from the 2620XM only by the presence of an additional Fast Ethernet port.

Figure 8.8 Physical appearance of the 2621XM router

Two of the free slots can be equipped with WIC modules, while the third slot allows you to mount an NM card, so you can significantly expand the functionality of the router.

Figure 8.9 Optional Equipment for 2621XM Router

Due to the fact that the optional equipment coincides completely with the equipment of the router version of the 2620XM version , we will not describe it again.

8.1.5 Series 2811

Another router available in the program is the 2811 series router. By default, it has two Fast Ethernet ports with a bandwidth of 10/100 Mbps, four WIC/HWIC slots for installing expansion cards and one slot for NM modules.

Figure 8.10 Physical appearance of Router 2811

Free router slots allow you to mount the following expansion cards:

Figure 8.11 Optional equipment for router 2811

 Configuring Cisco Routers

Other optional equipment has already been described in the case of the 1841 and 2620XM routers.

8.1.6 Series 2901

Another router available in the program is the 2901 series router. By default, it is equipped with two Gigabit Ethernet ports with a bandwidth of 10/100/1000 Mbps. It also has four slots for HWIC expansion cards.

Figure 8.12 Physical appearance of Router 2901

The optional equipment of the 2901 router includes:

Figure 8.13 Optional Equipment for Router 2901

All these components have already been described in the case of the 1841 router.

8.1.7 Series 2911

Another router available in the program is the 2911XM series router. By default, it has three Gigabit Ethernet ports with a bandwidth of 10/100/1000 Mbps, as well as 4 slots for HWIC expansion cards.

 Configuring Cisco Routers

Figure 8.14 Physical appearance of Router 2911XM

Optional equipment on the 2911XM includes:

Figure 8.15 Optional Equipment for 2911XM Router

This equipment coincides completely with the equipment of the 2901 series router, so we will not describe it again.

8.1.8 IR829 Router

Another router available in the program is the 800 series router. By default, it has three Gigabit Ethernet ports with a bandwidth of 10/100/1000 Mbps, as well as 4 slots for HWIC expansion cards.

The IR829 (Industrial Integrated Services Router) is a model of integrated industrial router that simulates an 800 series router, offering wireless and wired LAN connection, wireless 4G connection and fiber optic WAN connection.

 Configuring Cisco Routers

Figure 8.16 Physical appearance of IR829 router

Designed to work in harsh environments and to communicate with another AP access point or wireless controller of Internet omnipresent.

The router is equipped with:

 1 Wireless Access Point ( wlan-ap0 )

 1 GigaEthernet0 WLAN interface ( Wlan-GigabitEthernet0 )

 2 x 4G LTE network interfaces ( Cellular0, Cellular1 )

 4 Gigabit Ethernet LAN interfaces ( GigabitEthernet1 – 4 )

 1 free GE0 WAN slot where only the GLC-T module can be installed. The GLC-T module includes a single Gigabit Ethernet port and supports a Category 5 UTP cable up to 100 m long.

8.1.9 819IOX Router

The Cisco 819IOX (Integrated Services Router) is a model of router simulating the C819HG-4G-IOX router that supports M2M (Machine-to-Machine) applications and cellular network services.

Figure 8.17 Physical appearance of the 819IOX router

8.1.10 CGR 1240 Router

The CGR 1240 (Connected Grid Router) is a router model that simulates a 1000 series router. The main applications of this series of routers are: support for FAN (Field Area Network) distribution networks, integration of distributed solar farms, control of public lighting. It is shockproof and can be mounted on poles.

Figure 8.18 Physical appearance of the CGR 1240 router

The router is equipped with:

 1 Gigabit Ethernet interface ( GigabitEthernet0/1 ),

 1 x 802.11 wireless ( Dot11Radio2/1 )

 2 Giga Ethernet LAN interfaces ( GigaEthernet2/1 – 2/2 )

 4 Fast Ethernet LAN interfaces ( FastEthernet2/3 – 2/6 )

8.1.11 ISR 4321 Router

The ISR4321 router is mainly designed to offer advanced network services in small corporations. Its default total bitrate is 50 bps. By default, it has ports for management: USB and RJ-45, 2 Gigabit Ethernet ports with a bandwidth of 1000 Mbps for cable connection, as well as 2 slots for NIM-ES2-4 or NIM-2T expansion cards.

Figure 8.19 View of ISR4321 available in the program

 Configuring Cisco Routers

Figure 8.20 USB Console and Console ports on ISR4321

The router comes standard with:

 1 USB console interface ( USB Console )

 1 RJ-45 console interface ( Console )

 2 Gigabit Ethernet LAN interfaces (GigabitEthernet0/0/0

– GigabitEthernet0/0/1)

 2 free slots in which you can install only NIM-ES2-4 or NIM-2T modules NIM-ES2-4 or NIM-2T

The NIM-ES2-4 module has 4 Giga Ethernet ports for network switching.

Figure 8.21 NIM-ES2-4 module

The NIM-2T module has 2 ports for serial synchronous communication.

Figure 8.22 NIM-2T module

In addition, the GLC-LH-SMD or the GLC-GE-100FX can be inserted in place of the GigabitEthernet0/0/0 interface.

The GLC-LH-SMD module allows you to set up a Gigabit Ethernet connection using a single-mode fiber.

Figure 8.23 GLC-LH-SMD module

The GLC-GE-100FX allows you to set up a Gigabit Ethernet connection via multimode fiber for distances of up to 2 km .

Figure 8.24 GLC-GE-100FX module

8.1.12 819IOX Router

The Cisco 819IOX (Integrated Services Router) is a model of router simulating the C819HG-4G-IOX router that supports M2M (Machine-to-Machine) applications and cellular network services.

Figure 8.25 Physical appearance of the 819IOX router

The 819IOX comes standard with two antennas and non-replaceable antennas:

 1 GigabitEthernet0 interface

 4 FastEthernet0 interfaces – FastEthernet3

 1 Serial0 serial communication interface

 1 Ethernet1 interface

 1 VirtualPortGroup0 port

 1 Cellular0 cellular network interface

8.1.13 819HGW Router

The Cisco 819HGW (Integrated Services Router) is a variant of the C819 router model that supports M2M (Machine-to-Machine) applications and cellular network services.

 Configuring Cisco Routers

Figure 8.26 Physical appearance of the 819HGW router

The 819HGW comes standard with five antennas and non-replaceable antennas:

 1 GigabitEthernet0 interface

 4 FastEthernet0 interfaces – FastEthernet3

 1 Serial0 serial communication interface

 1 Ethernet1 interface

 1 Gigabit Ethernet Wlan-Gigabitethernet0

 1 Cellular0 cellular network interface

 1 internal module acting as an access point wlan-ap0

8.1.14 Series PT Router

The last router that we will discuss is the PT series router. We distinguish two such routers – it is a PT-Router and a PT-Empty router. The difference between them is only due to the fact that the former has already completed 6 slots for network cards, and the latter is completely empty - it has ten slots in the place of which we can mount the interface of our choice. The first one has two Fast Ethernet ports with a bandwidth of 10/100 Mbps using twisted pair cables, two Fast Ethernet ports with a bandwidth of 10/100 Mbps in the fiber standard and 2 serial interfaces for fast WAN connections.

Figure 8.27 Physical appearance of the PT-Empty router

In free slots we can install the following components:

Figure 8.28 Optional equipment of the PT-Empty router

Below is a detailed description of the individual components:

PT-ROUTER-NM-1AM PT-ROUTER-NM-1CE

Single connector type RJ-11, Single Ethernet port with bandwidth 10/100 Mbps

PT-ROUTER-NM-1CFE PT-ROUTER-NM-1CGE

Single 10/100Mbps Fast Ethernet Single Gigabit Ethernet port with port 10/100/1000Mbps bandwidth

PT-ROUTER-NM-1FFE PT-ROUTER-NM-1FGE

Single 10/100Mbps Fast Ethernet Single 10/100/100Mbps Gigabit port in fiber optic standard Ethernet port with fiber optic PT-ROUTER-NM-1S PT-ROUTER-NM-1SS Single serial port used for Intelligent serial connector supporting a

connections remote locations or wide range of interfaces when using older network devices suitable adapter cables

8.2 Configure Cisco Routers Using the Graphical Interface

8.2.1 Interface Configuration

Router configurations in the Cisco Packet Tracer will start with configuration using the GUI, i.e. the graphical interface. Later we will go to the configuration using commands (CLI), which gives us much more possibilities, but before that we want to get to know our program as best as possible so we will see the pros and cons of using the graphical interface. First, let's create a simple topology consisting of one computer and one router (we will use a PT-Router).

Figure 8.29 Basic topology for router configuration

For the connection to work properly, you must configure both devices. In this example, we will use a network with the address 200.200.200.0 and a network mask of

255.255.255.0. The configuration of computers has already been described in detail in the subsection Basic configuration of devices , so we will not describe it here.

Figure 8.30 Addressing a computer

Now, in order for the connection to start working, you need to configure the interface of the router. To do this, click on the router, and then in the Config tab select the appropriate interface from the list - what interface has been connected can be determined in two ways. The first way is to remember which interface the cable is inserted into. The second way is shown in the figure below and consists in enabling the Always Show Port Labels in Logical Workspace option in Options-Preferences so that, as in the picture, you will be able to see device ports in a logical topology.

Figure 8.31 First step - displaying interfaces on the logical topology  Configuring Cisco Routers

Figure 8.32 The second step - displaying the interfaces on the logical topology Returning to the configuration of interfaces - in the Config tab in our case, we select the Fast Ethernet 0/0 interface ( Fa0/0 ) and give it an IP address in accordance with previous assumptions.

Figure 8.33 Router Interface Configuration - GUI

As we can see in the figure above, the configuration via GUI is similar to the configuration of other devices, e.g. PC, only in this case at the bottom we have an additional window that reflects what we do in the GUI only in the form of commands. If you want it now you can observe what the form of commands looks like, so it will be easier for you to configure routers later using the CLI.

Now to check if our configuration works correctly, first look at the LEDs - if both are green, it means that the ports are in the Up state. Next, PING PC1 to the configured router interface.

Figure 8.34 Successful PING from workstation to router interface The connection is already configured and working. However, if we stop there and the router is turned off or restarted, its entire configuration will be lost. To prevent this, save the current configuration as a start-up configuration. Thanks to this, if the router is turned off or restarted, we will not lose its settings. To be able to save the configuration in the first place, we need to open the Settings window from the Config tab, as shown in the figure below.

 Configuring Cisco Routers

Figure 8.35 Settings tab in the router

As you can see, in addition to saving, we have several general options at our disposal here. Using the Display Name field, we can change the name of the device label displayed in our topology. The Hostname field allows us to change the name of the router under which it appears in IOS. It is very important to understand the important difference between Hostname and Display Name – Hostnam e is an actual parameter of a network device that is important in many configurations, for example in the PAP and CHAP authentication protocols. Display Name is just supporting text (the description shown below the device) in a logical topology.

Further options are already directly related to saving and loading configurations. To save the current configuration as a start-up configuration, click Save . The Erase button, in turn, allows us to reset the start-up configuration. Under the line separating the buttons there is an option that allows us to export ( Export ...) and import ( Load.../Merge ...) the configuration of the router from a text file on the computer disk. Start-up Config refers to the start-up configuration, while Running Config refers to the current configuration. In our example, we need to click the Save button, saving the current configuration. Now the router configuration will no longer be lost.

8.2.2 GUI-Configurable Routing Protocols

As we probably know, the main task of routers is to carry out routing , i.e. to indicate the way for packets to the target host (network). Routers owe this functionality to various routing protocols – there are many of them and in this book we will discuss the most important of them, theoretically and practically. However, with the help of GUI we are able to configure only two types of routing - static routing and the simplest routing protocol, i.e. RIP.

8.2.2.1 Static Routing

Using static routing, we have to manually assign a packet route to each network we want to communicate with. This is a good solution for small networks and the only routing protocol that does not learn routes on its own. In order to present this way of routing, we will create the following topology consisting of 3 routers and 3 computers:

Figure 8.36 Test topology

As you can see, all connections are disabled and you need to use the knowledge described earlier to configure and run the interfaces. In this topology, there is a serial connection between the routers. When configuring them, we must remember to set the Clock Rate on the DCE device. Select this value from the drop-down list. If you do not know which device is DCE and which is DTE, just look at the connection with the Always Show Port Labels in Logical Workspace option enabled. When marking the interface of one of the routers, a clock icon will be shown – it is a DCE device.

 Configuring Cisco Routers

Figure 8.37 Specify a parent clock

A properly configured serial interface on a DCE device looks like this:

Figure 8.38 Properly configured DCE serial interface

In the case of the DTE interface, we do not simply change the Clock Rate value due to the fact that the other side of the link will negotiate this value. The next step after addressing each router interface is to address the end devices as we see in the figure below. In the case of connections to computers, we always give the first address from the pool - then we have more order in the network.

Figure 8.39 Correct configuration of the end device

As you can see, this time, we enter the address of the Default Gateway , that is, the default gateway. The default gateway is the nearest router on the network, thanks to which we will be able to communicate with other networks. It is not needed until we communicate with external networks (outside access from the local network). After addressing the devices, we can test our network, how it works. We will try to send a PING command from one of the devices first to the default gateway and then to another device.

Figure 8.40 PING from workstation to default gateway and end device PC1 has no problem communicating with the default gateway, due to the fact that it is in the same network.

When we try to communicate with a host on another network, a router without a configured routing protocol will not know where that network is located and returns a packet saying that the destination host is unavailable.

In order for our router to know where the target network is located, it should be indicated to it in the case of static routing.

 Configuring Cisco Routers

Figure 8.41 Static Routing Configuration - GUI

In tab [ Config  Routing  Static ], we can specify the target network together with the mask and the address of the Next Hop , i.e. the address of the router to which the packet is to jump to find the way to the target network. In our case, we have a network of

192.168.2.0, which is located "at the top" of our topology, so we direct packets to the address 200.0.0.2, which is the address of Router 2. Remember to always determine the way back and forth! Otherwise, routing will not work.

Now, after pinging other networks, everything works as it should.  Configuring Cisco Routers

Figure 8.42 Correct PING to other networks - static routing

8.2.2.2 RIP Routing Protocol

Now that we have learned the assumptions of routing protocols and how the router works , we can move on to the first dynamic routing protocol - RIP (Routing Information Protocol).

Dynamic routing, which is one in which routers can exchange topology information with each other and complete their routing tables. This solution is much faster than manual configuration of all routes, and in the event of a failure of one of the links, routing will automatically redirect traffic to another (if available). Let's start with a slightly more elaborate topology:

 Configuring Cisco Routers

Figure 8.43 Topology with device addressing for RIP

In the above there are 5 routers and 9 networks. If we wanted to manually assign a route to each network, it would take a lot of time, but with RIP it is much simpler. All connections are disabled, so first we need to configure the computers and interfaces of the routers as described earlier.

Figure 8.44 Topology after configuration

After correct configuration, all LEDs should be green, however, we can not communicate with remote networks.

 Configuring Cisco Routers

Figure 8.45 PING Command Results

We will now proceed to configure the RIP protocol. To do this, click on the router, enter the Config tab, and then select from the list on the left side of the RIP .

Figure 8.46 RIP tab

To configure the RIP protocol, we must enter in the Network field the address of each network that is connected directly to the router interface. For example, in the case of Router 1 , these will be: 192.168.0.0, 200.0.0.0 and 200.0.1.0. Each entry is approved by the Add button, while using the Remove button we can delete already existing entries or possibly correct incorrect entries.

 Configuring Cisco Routers

Figure 8.47 Properly configured protocol on Router 1

Similarly, other routers should be configured. Once you have configured them all, communication between all networks will be possible.

Figure 8.48 PING results after correct RIP configuration

As we can see, the routers themselves determined the route of the packets and delivered them to the destination. The RIP protocol uses the number of hops (routers) on a given route as a metric when choosing a route, always choosing a route with as few hops as possible. The route of packets can be checked in several ways, for example by using the tracert command or graphical ping in simulation mode. So let's check the packet route between PC1 and PC2 in the latter way.

 Configuring Cisco Routers

Figure 8.49 Package route between PC1 and PC2

As you can see, the packets pass through routers 1, 2 and 3. Now let's see what happens when we turn off Router 2 .

Figure 8.50 Package route between PC1 and PC2 after updating the routes After a while, the routers updated the routing tables and set a new route. This time, the packets ran through routers 1, 4, 5 and 3, bypassing the disabled router 2. If we were using static routing, the administrator would have to manually update the routing tables. RIP did it automatically.

8.3 Configuring Cisco Routers in Cisco IOS As we could see earlier, the Config tab located in the graphical interface for configuring the router does not have many options to configure, so it is recommended to configure routers in the Cisco IOS, i.e. using commands.

8.3.1 Basics

If you want to start configuring the router in a real environment, you will need to have any computer with a COM port (RS232), a console cable and, of course, the router.

Figure 8.51 Steps to connect a computer to a router using a console cable The correct connection of the computer to the router is shown in the figure below. However, it should be remembered that the console cable is used only for the configuration of the device.

Figure 8.52 Correct console connection

Now it's time to try to connect to the router. For this we will need an application on the desktop of the computer called Terminal .

Figure 8.53 Terminal

After starting Terminal , a configuration window appears in which you should not change any parameters. Leaving, so the default settings, we click on the OK button, after which the connection to the router should take place.

Figure 8.54 Terminal configuration window

After the correct connection, a window should appear, shown in the figure below. The last line of the console with the text: Continue with configuration dialog? [yes/no]: Indicating that the connection was correct and the router's operating system is waiting for the user to make a decision.

` Figure 8.55 Log in to the router correctly

It may happen that when trying to connect to the router, the console window will be empty, which may mean that there is no connection between the devices, but the most common reason is a disabled router. On the other hand, when we have the terminal window open and the router has just been turned on, we can see the progress of extracting the system image, which can be seen in the figure below:

Figure 8.56 Extracting the system image by the router

Let's move on to the configuration of the router connected by a patch cable to the computer through the CLI console.

Figure 8.57 Computer connected via patch cable to the router

8.3.2 Wizard Mode

In the case of configuring routers from the IOS level, we have two options: through the wizard or without its use. In this chapter, we will discuss the wizard mode. If you want to start the wizard mode, you should answer the first question in the console: Continue with configuration dialog? [yes/no], answer yes and press Enter . After a while, the console window will change the content to the following form:

 Configuring Cisco Routers

Figure 8.58 Wizard mode selection - simple or advanced

8.3.2.1 Simple Wizard Mode

This is a wizard mode in which the simplest router settings are available for configuration without knowing any commands. To get to it, you need to answer the question: Would you like to enter basic management setup? answer yes .

After a while, another command will appear in the terminal window: Enter host name [Router ]:p at which we have to give the name of our router

Note, however, that this time the hint that the device gives us is unambiguous, because in square brackets there is one word: [Router], and not as it was previously two: [yes / no]. This means that it would be enough to press enter and the router would be given the default name, suggested in square brackets. However, in this configuration step, we can enter a different name, for example Router123 , as shown in the figure below.

Figure 8.59 Naming a router - simple wizard

After confirming this step, you must enter three passwords, one in turn, which will protect against unauthorized access to the privileged mode of the router (the modes of operation of the router are described in the next chapters of the book).

 Configuring Cisco Routers

Figure 8.60 Giving passwords to access the router - simple wizard First, we are asked to enter the password for the privileged mode in general. Then we are asked again to enter the password for the privileged mode, which works in older versions of the software. The last password we are asked for is the virtual access password, which secures the router when someone tries to log in to it over the network (using protocols such as Telnet or SSH, which will be described later).

The next question concerns the Simple Network Management Protocol (SNMP), which allows the exchange of control information between network devices, but will not be described at the moment, so we answer this question no .

Figure 8.61 SNMP configuration question

After performing the above actions, the router displays the status of its interfaces, after which it asks us which interface we want to configure. in our case it will be FastEthernet0/0 . Then the router asks if we want to configure the IP address on this interface - press enter or type yes . The next step is to assign any IP address to the interface, in our case, it can be 192.168.0.1 with a subnet mask of 255.255.255.0 (as the router tells us).

 Configuring Cisco Routers

Figure 8.62 Configuration of interfaces - simple wizard

Then the router will display the configuration and we will be able to finish the wizard by selecting one of the options (Save this configuration to nvram and exit).

Figure 8.63 Completion of configuration - simple wizard

The first option allows us to go to the IOS level without saving the configuration displayed above. The second, in turn, allows us to return to the simple wizard also without saving the configuration. The last option saves the configuration to startup-config , i.e. the one that will be loaded after the router reset, and exits the configuration window. We are interested in the latter option, which is why we choose it. Now it remains for us to address our Laptop and conduct a connection test using the PING command.

Figure 8.64 Test the connection between the laptop and the router

8.3.2.2 Advanced Wizard Mode

Advanced mode is not very different from simple mode. After the first start of the router, we will be asked if we want to enter the wizard mode (as we described in the previous subsection) and this time we also answer in the affirmative. The second question is the same as in discussing the previous mode, but now we answer negatively so that we go to the advanced wizard mode.

Figure 8.65 Enter the advanced wizard mode

First, we are asked if we want to display the current state of the interfaces - this is an option that better allows us to illustrate the current situation on the network. We answer in the affirmative.

Figure 8.66 Current status of interfaces - advanced wizard The next steps are similar to those in a simple wizard, as we have already discussed them, we will configure them the same as before:

Figure 8.67 Router Name, Passwords and SNMP Configuration - Advanced Wizard The next question is about the configuration of the interfaces, but this time we do not choose which interface specifically we want to configure, since we will be asked in turn about each. In our case, we will only configure FastEthernet0/0 in the same way as before ( 192.168.0.1/24 ), and the rest of the interfaces will be omitted.

 Configuring Cisco Routers

Figure 8.68 Interface configuration - advanced wizard

Just like in the simple wizard, the last step is to view the current configuration and the same three steps. As before, we select the last option and save the configuration. Now let's address the computer and see if it can send PING to the FastEthernet0/0 interface of the router.

Figure 8.69 Saving the current configuration - advanced wizard  Configuring Cisco Routers

Figure 8.70 Test the connection between the laptop and the router We have the same situation as before - the configuration is correct.

8.3.3 Basic Router Configuration Modes

The modes of working with the router in wizard mode described above allow only for its basic configuration, which does not satisfy us, due to the fact that the options that interest us are definitely more advanced. Therefore, we will now describe the individual steps leading to the configuration of the equipment using the manual method.

8.3.3.1 Console Mode Support

In this section we will describe how the so-called "modes of operation" can be used. Each of these modes will serve for something different. Most often, after switching on the router, the console screen will show the process of loading and decompressing the IOS image, and then the router will ask us if we want to use the wizard, the operation of which we described above. After answering the question in the negative, we will be transferred to the user mode , which is used for typical tasks related to checking the status of the router, but you can not make any changes in the configuration here. To easily recognize modes and distinguish them from each other, each mode has a different "prompt" after which the user will enter commands. In user mode, the prompt is: Router>. The following figure shows the basic modes of operation of the router and the commands for moving between them.

 Configuring Cisco Routers

Figure 8.71 Navigating between basic router modes

According to the graph above, let's now try to move to the next mode of operation of the router – Privileged Exec Mode , a mode used both to display the status of the configuration of the hardware, memory, operating system, but also to issue simple diagnostic commands, e.g. PING, TELNET, TRACERT , etc. We enter this mode with the enable command, and the router's prompt changes to Router#.

The third mode, which is described in this subsection, is the Global Configuration Mode , used both to configure various elements of the router, and from this mode we will move to the next configuration modes, in which we will define almost all components of the equipment and its equipment. You can only enter the global configuration mode from privileged mode by typing the command: configure terminal , after which the router greets us with the Router(config#) prompt.

Figure 8.72 Navigating between basic router modes

Figure 8.73 Router splash screen

8.3.3.2 Using Help

Very often, when working with operating systems from the command line, administrators use help to check the syntax or application of a given command. The situation is also similar in the IOS system of CISCO routers. Therefore, we will now describe how we can use it. As we mentioned earlier, each of the router modes has a different use, which is why it will contain different commands that can be used in each of them separately. To call up a list of commands available in a given mode, type a question mark: ?, and then press Enter .

Figure 8.74 List of commands in user mode

We will not describe the meaning of all commands. We will show their application in specific situations. When we call in the same way help in privileged mode, sometimes we can notice that there are many more commands, and they may not even fit all in one console window, and at its bottom you may see the inscription: --More--. If you want to call further commands, you can best use two keys: spacebar – displays the next line, while the Enter key – displays another screen.

 Configuring Cisco Routers

Figure 8.75 List of commands in privileged mode

Another very useful feature of the IOS system help is to suggest further syntax of more complex commands or their automatic completion. We will use for this purpose an example in which we deliberately simulate a certain error that very often happens when working with the command line. We will go to the privileged mode and try to call help for this mode by typing the command: help . After a while, it turns out that the console displays the message: Translating "help"...domain server (255.255.255.255) and we can not type anything. To avoid this inscription, press Ctrl+Shift+6 and then release all key. Please do not be afraid, after a while we will regain access to the router, and this is because there is no such command as help (calling help is possible only by using the sign: ?). At the moment of mistyped command, the router begins to search for the names of some host with the specified name or a computer with this address. When, of course, it does not find anything, it will display the second part of the message: % Unknown command or computer name, or unable to find computer address , and immediately returns to our control over the router.

 Configuring Cisco Routers

Figure 8.76 The result of typing an incorrect command

For those who are impatient, we provide a very useful keyboard shortcut that causes an immediate return to the command line level. This is Ctrl+Shift+6 . Let's assume that we now select the privileged mode and the clock command to show how else we can use the help and hints of the IOS system. Probably everyone knows what this command will be used for, and its name is also not alien to anyone, but let's assume a situation in which we forgot its name, we only know what letter it began with. It is enough to write this letter and immediately after it press the question mark (?), as shown in the figure below. The router will then display all commands starting with the indicated letter and available in a given mode. Of course, you can enter the first few letters and press the question mark, but we must remember that there is no space between the questioner and the letters you type.

Figure 8.77 Display commands that begin with a letter

There may also be an event in which, after typing the correct command, you receive the error message:  % Incomplete command ., which means that the entered command is not complete and most likely you need to finish its phrase.

Figure 8.78 Enter an incomplete command

Therefore, if you want to check what is its further syntax, you should use the question mark again after entering an incomplete command. However, it should be separated by a space, as shown in the next figure. Then, on the next line, you will see a hint about the further syntax of the command and its explanation.

Figure 8.79 View further command syntax

With this method, acting in an analogous way, we can learn the full syntax of this basically simple but complex command, in which the time and date separators are important, as shown in the figure below.

Figure 8.80 Type the full command after using help

Another important feature that makes life easier is using the Tab key to automatically complete typing commands from the keyboard. That is, when we type an incomplete command, for example clo and press the Tab key, it will be filled automatically for the user, obtaining the effect: clock .

It is also worth remembering that through the arrow keys ↑ ↓ you can view the history of entered commands and using these keys, you can call previously entered commands. There may be a situation in which we make a mistake in the syntax of a command consisting of several members, as an example we use the command: configure terminal and intentionally simulate the so-called letter error, consisting in the fact that in the syntax of the second part of the command instead of the letter " n " we enter " d ". Then the router will point out that we made a mistake by displaying the message: % Invalid input detected at '^' marker . and the sign: ^ will indicate its location. This situation is shown in the figure below. This is very helpful, because sometimes it is difficult to notice the location of the error, and in this situation it is very easy.

Figure 8.81 Error message in command syntax

It is also worth knowing that working a little longer with the IOS system, and wanting to speed up the hardware configuration process a bit, administrators very often use shortcuts of known commands. Shortcuts are simply the first few letters of IOS commands that can be used at any time, but remember not to shorten the commands too much. That is, if we shorten the command to such an extent that the string we entered will be the equivalent of two or more commands, then the router will not know what command is in question and will return us an error message:% Ambiguous command: "dis", and an incomprehensible string will be marked in quotation marks. The use of shortcuts and a possible error message is shown in the next figure.

Figure 8.82 Use shortcuts

8.3.3.3 View the Status of the Router

Before or during the configuration, and very often when solving various problems with routers, you will need to view the status of the device, preview the configuration, etc. For this purpose, we will use the show command, which we will now present. This command is used in privileged mode, and its use is very rich. However, we will not present all its capabilities, we will only show what it is for, and its use will be known to everyone during everyday work with the router. In order to check the enormity of the possibilities of this command, let's call the help, the command show ?, as shown in the figure below.

 Configuring Cisco Routers

Figure 8.83 Help for the show command is displayed

The first of the commands of this type will be: show version – through it we can check the version of the IOS system, the location of the system image file and its name .

Figure 8.84 Show version command

Another very useful command is show ip interface brief , a command with which we can display the status of all router interfaces and assigned IP addresses, as shown in the figure below.

 Configuring Cisco Routers

Figure 8.85 Show ip interface brief command

The show running-config command is the most commonly used command by people who verify the configuration of the router or want to solve existing problems with the hardware configuration itself. However, we must remember that with its help, we display a temporary configuration, saved in RAM. To display the status of the configuration stored in non-volatile memory (NVRAM), we use show startup-config command.

Figure 8.86 Show running-config command

Through the show flash command, we can display information about the amount of occupied flash memory of the router, through all the files placed inside it.

 Configuring Cisco Routers

Figure 8.87 Show flash command

Through the show ip route command, we can display the status of the routing array.

Figure 8.88 Show ip route command

8.3.4 Configure Router Name, Passwords, and Message Of The Day (MOTD) Another basic configuration step is to define the name of the router, which will make it easier to identify it in complex and extensive networks. The name of the router is configured in the global configuration mode, for this purpose it is not required to go to a specific configuration mode. If the name is not configured, IOS displays a prompt that precedes the default device name, Router .

We must remember that it is often not enough to place the description ( Display name ) of devices in the designed logical topology, although this action is very important. In addition to the above-mentioned fact, it is advisable to give the device a name ( Host name ) in the IOS system itself.

Figure 8.89 Display name in logical topology

If you want to enter a device name ( Host name ), use the command: hostname, and after the space you enter a new name. For example: hostname ITSTART . When you do this, the prompt changes as shown in the figure below.

Figure 8.90 Define a router name (Host name)

Each router should be properly protected against unauthorized access by third parties. For this purpose, passwords are used to protect both the entrance to the router from the console and virtual terminals (Telnet, SSH), as well as the transition from user mode to privileged mode . Describing the protection of the router with passwords will begin with the latter, because we will present two previous cases in the subsections devoted to the configuration of consoles and virtual terminals.

The password for the privileged mode, like the name of the device, is entered from the global configuration with the enable password command (then we enter the password, which will be saved in running-config in an explicit form) or enable secret (the password that we will give will be in encrypted form) and after the space we enter the password we are interested in (for example: "admin" and "admin1").

After the above actions have been performed correctly, we will check the correctness of our actions, so we will go to privileged mode , and then to user mode to re-enter privileged mode . We note that the router now requires us to enter the password that we have previously defined. As enable secret is safer, it will be the priority and we will have to give it.

Figure 8.91 Define a privileged mode password

When you view the current configuration, you may notice that the first password is plaintext and the second is encrypted.

Figure 8.92 Unencrypted and encrypted passwords in the current configuration To encrypt all passwords that exist on the router, execute the service password-encryption command presented below. When you view the current configuration again, you can see that both passwords are encrypted.

Figure 8.93 Encrypt passwords on your router

Now we will present the possibility of displaying the welcome text on the console, i.e. a banner (the so-called Message of the day), which can be a greeting for users who will connect to the router. To do this, in the global configuration mode, execute the command: banner motd (and after a space press the character that will be the beginning for the text you are entering, similarly typing the same character a second time will mean the end of the text string). In the figure below we have an example configuration of the message of the day.

Figure 8.94 Message Setup of the Day

In order to check whether the message will be displayed correctly after entering the router, type exit , disable , and exit again to see the message informing us about entering the router.

Figure 8.95 Router welcome window

We are now in the console window that informs us of the correct connection to the router. When you press Enter , a welcome message will be displayed.

Figure 8.96 Message Of The Day (MOTD)

8.3.5 Other Modes of Operation of the Router

In order to start configuring CISCO routers, in addition to knowing the basic modes of operation previously learned, we need to know several new ones, with the help of which we will be able to fully set the basic parameters of the router. All the modes listed below are switched from the global configuration mode, which is the initial mode from which we must start working.

Figure 8.97 Other router modes

8.3.5.1 Console Port Configuration

Above we have described how to partially protect our router against unauthorized access. Now we will focus on how to configure and also secure access to the router from the console and virtual terminals. We go from the global configuration mode to the console configuration mode with the line console 0 command, then enter the command: login, which will force the user authorization and define the password after the password command (in our case, let it be: console ). Finally, finishing the configuration, we can leave the mode with the exit command.

Figure 8.98 Console port configuration

Before we test the console port configured just now, and more precisely its protection via a password, we will show that in addition to the previously set so-called message of the day , you can set a welcome message , which will be additionally displayed when logging in to the router through this port. For this purpose, the banner login command is used, the text entry is done in the same way as in the case of the banner motd command . The whole procedure is illustrated in the figure below.

 Configuring Cisco Routers

Figure 8.99 Set up a welcome message

To check the correctness of our actions, let's go to the splash screen, then press Enter and after a while both messages will appear on the screen and two-step authorization is active as shown in the figure below.

Figure 8.100 Message Of The Day and welcome message and user authorization

8.3.5.2 Configuration of Virtual Terminals (Telnet, SSH) We have just learned how to configure and secure the entrance to the router from the console from the computer, which is most likely located near the router (most often in the same room). However, it rarely happens that our router would not be connected to any network, which is why it is possible to configure it remotely via LAN or even WAN. We will use an example in which our router is configured to work in a LAN to which desktop computers are connected, as in the figure below.

Figure 8.101 Topology for router configuration using a virtual terminal - Example

8.3.5.2a.pkt

Entering the virtual terminal configuration mode is very similar to the console, in the global configuration we enter line vty 0 4 (the range between the first and second number is the number of channels that can be used by several people working remotely on the router at the same time – in our case, the range from 0 to 4 means 5 users at the same time). Then execute the login and password commands (in the same way as in the case of the console port), as shown in the figure below.

Figure 8.102 Basic configuration of the virtual terminal

The maximum range of channels to configure can be 16 (that is, from 0 to 15). It should also be remembered that for different ranges we can define different passwords. We will not describe it, we leave it to the reader for their own exercises. However, we will now try to check the correctness of our previous actions, i.e. connect to the router remotely We run the command line from any LAN computer, using the Command Prompt application, available on the computer's desktop. After starting the command line, type telnet 20.0.0.1 (where the IP address is the address of the router interface). After a while, we get a connection to the router, we authorize ourselves according to the configured passwords. We can go into global configuration mode and start managing the router remotely.

Figure 8.103 Access to the router via Telnet protocol

It is also worth remembering that from the router itself you can also call a TELNET connection to another router. For this, we will now demonstrate a situation in which we log in from the computer to the intermediate router, and from it to the next router. An example of a topology is shown in the figure below. We assume that the Internet Provider router has been password protected with the password ’hardpassword’ .  Configuring Cisco Routers

Figure 8.104 Topology to configure a telnet router from another router First, we run the command line of any computer, and then connect to the Internet Provider router by executing telnet 20.0.0.1 , and entering the hardpassword password. After correct authorization, we can execute the telnet 10.0.0.1 command from user mode to connect to the ITSTART router. The whole procedure is shown in the figure below.

Figure 8.105 Indirect connection to the router via Telnet

Later in this section, you will describe the basic Telnet configuration of SSH . It is a much more secure cousin of the Telnet protocol. SSH uses only encrypted connections, and Telnet transmits all data as unencrypted.

Figure 8.106 Topology for configuring SSH connections

To configure SSH access, on the router to which you want to have access, you must first create a user to whose account you will be able to log in. In our example, it will be admin with admin . Then we can choose on which channels we will connect the SSH protocol with the router (e.g. 5 and 6) and on them you need to specify two things: login local l or log in to the router you can only on the user created on this router and transport input ssh so that you can use the SSH protocol.

Figure 8.107 Adaptation of the virtual terminal to SSH connections The next step is to specify the domain name ( ip domain-name ) that is needed to identify the keys and generate this key pair, which will be used to encrypt the information sent between the user and the router. (details about connection encryption and network security are not included in the scope of the information described in this book.)

Figure 8.108 Domain name and RSA key generation

From this point on, you can connect to the router using an encrypted SSH connection. In order to connect to the router with the address 20.0.0.1 to the admin account, type the command ssh -l admin 20.0.0.1 . in the Command Prompt command line. Successful connection and login to the router is shown in the figure below.

Figure 8.109 Successful SSH connection to router

8.3.5.3 Interface Configuration

One of the most important activities when setting up CISCO routers is the ability to prepare router interfaces for everyday work. Knowing the specifics of routers from the initial chapters of the book, we know that we can deal with interfaces: Ethernet, Fast Ethernet, Gigabit Ethernet (using copper or fiber optic media) or with serial interfaces. Let's start with the configuration of the Ethernet interface. For this purpose, we will connect the router with any computer with a Fast Ethernet interface in copper technology. A patch wire will be required for this type of connection.

After connecting the router to the computer with the appropriate cable, the topology should look as shown in the figure below. It is a good idea to determine the IP addressing in the topology at the beginning of the configuration.

 Configuring Cisco Routers

Figure 8.110 Topology for Configuring Fast Ethernet Interface In the first place, we can set a static IP address on the computer, according to the figure above it will be 50.0.0.2/24. After performing the above action, the LEDs at the interfaces still remain red, because the connection is still not fully functional. To start connecting to the router, you must configure the interface on the router. The easiest way is to enable the Always show port labels in Logical Workspace option in Preferences to see which ports we have connected devices to.

Figure 8.111 View of interface numbers in a logical topology At this point, you can go to the IOS system of the router to make the necessary configuration changes. To do this, switch to global configuration mode to go from it to Fast Ethernet configuration mode.

Figure 8.112 Switch to interface configuration mode

Then you need to define the IP address, according to the previous assumptions, it will be

50.0.0.1/24 . To do this, type the command: ip address 50.0.0.1 255.255.255.0 , press Enter and in order to enable the network adapter, type : no shutdown . After a while, we notice that two messages are displayed on the screen:

%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up.

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up.

The messages mean that both the network adapter and the protocol itself have changed their state from " down " to " up ", which means that the Fast Ethernet network adapter has been enabled and configured correctly.

 Configuring Cisco Routers

Figure 8.113 Address the interface and enable

As we can see in the diagram, the diodes lit up green and we are able to carry out the test with the PING command.

Figure 8.114 Correct configuration and PING test

You can also use the connection test on the other hand, which is to send ping from the router to the PC. To do this, enter privileged mode and type ping 50.0.0.2 . As we note in the figure below, the packets have reached their destination 100%, however, the display of the PING response in IOS is slightly different than in the command line of the computer.

Figure 8.115 PING command from router to computer

The configuration of the other Ethernet ports in CISCO routers is almost identical, so we will not discuss them in detail. The configuration of serial interfaces deserves a bit more attention, which we will present below.

Let's assume that we modernize our existing topology with another router (also in version

1841) which we connect to the second one via a serial cable. Note that none of the routers we have used has a suitable network card by default, which is why we need to install the appropriate equipment on their panels. First, turn off the devices, and then drag to the free slots one WIC-1T module for each device.

Figure 8.116 Serial module WIC-1T

Figure 8.117 Router 1841 with WIC-1T module installed

Then we select any of the wires: Serial DCE or Serial DTE , after which we make a connection between the routers. An example of a topology is shown in the figure below.

Figure 8.118 Topology for serial connection configuration

We can now proceed to the configuration. Differences in serial cabling can be noticed only in the fact that only with one device, there is a clock icon (in our case it is visible at the bottom router). Here it should be remembered that each serial cable has the same plugs on two sides, but marked in a different way: one of them is DCE , and the other DTE . The difference is that the router to which the DCE plug is connected will broadcast the so-called Clock Rate , and the second of them will adapt to this frequency. There will also be a small difference when configuring the DCE interface.

 Configuring Cisco Routers

Figure 8.119 DTE and DCE serial interface

So, let's start with the configuration of the top router. After entering the global configuration mode , type the command: interface serial 0/0/0 (to enter the serial interface configuration mode ), then define its IP address and mask: ip address ip address 50.0.1.2 255.255.255.252 and finally turn on the interface with the command: no shutdown (or using the abbreviation no shut as shown in the figure below). However, we note that the interface has changed its state (it is still in the " down " state) %LINK-5-CHANGED: Interface Serial0/0, changed state to down . Only after configuring the serial interface in the second router will it change its state to " up ". The last action that we have to do, but only on the router to which the DCE plug is inserted, is to set the previously mentioned Clock Rate parameter. For example, we will enter clock rate 1000000 , which will be equivalent to a speed of 1 Mbps.  Configuring Cisco Routers

Figure 8.120 Configuration of serial interfaces

To check the correctness, we execute the PING command, for example from the top router to the bottom router. If the test passes correctly, it means that the configuration went without reservations.

Figure 8.121 PING command from top router to bottom router When addressing routers, we must pay attention to one very important issue, namely remembering that on each interface of the router there is a different pool of IP addresses, or a different subnet, if a subnet is used. If we happen to have an error in such addressing of devices as shown in the figure below, then the router will display error messages in the configuration, which is shown in the next figure.

Figure 8.122 Logical topology with incorrect addressing

 Configuring Cisco Routers

Figure 8.123 Consequences of poor addressing of interfaces You have to reckon with the fact that sometimes the router will not display a message about the wrong addressing of the device and then the error is more complex because in the future with more complicated configurations it will be very difficult to find such a small error. Therefore, you need to be very careful when addressing devices.

8.3.5.4 Configuration of Sub ‐ Interfaces

The use of so-called sub-interfaces is a feature of the CISCO device, which allows you to divide one physical interface into many logical (virtual) sub-interfaces . Sub-interfaces can be configured on CISCO routers in the same way as physical interfaces. This function is useful, for example, when configuring the so-called router on a stick . In this case, no IP address is configured on the physical interface. You only need to enable it, and set the IP addresses on the sub-interfaces as shown in the figure below.

Figure 8.124 Configure the sub-interface on the router

You switch to a sub-interface by using the command interface <main interface> . In this example this is a command: interface FastEthernet0/0.10 . When you enter the sub-interface configuration mode, the prompt changes to Router(config-subif)#. However, when you try to address a sub-interface, you will receive a notification that the IP configuration is only available if you configure the sub-interface as part of the IEEE802.10 , IEEE802.1Q , or VLAN protocol. Currently, nothing comes of it, but it will be explained when describing the configuration of the switches.

8.3.6 DHCP Configuration

DHCP configuration is also possible on the router and is described in this section. Let's build a simple topology consisting of two routers, one switch, and three computers.

Figure 8.125 Topology for configuring DHCP on the router In our example, we will configure the DHCP service on the DHCP router. We start by addressing the connection between the Router and DHCP devices. Next, let's address the second interface of the Router device, since this device will act as the default gateway for end users who retrieve IP addresses dynamically. Let's also use a simple command that will show the DHCP router where the 10.0.1.0 network is located. The router does not broadcast the networks to which it is connected, so the other router does not know anything about them. Routing protocols will be discussed later, but the ip route 10.0.1.0

255.255.255.0 gig0/0 command, which defines a static route in the DHCP router, is needed to perform the task correctly.

Figure 8.126 Indication of the way to the network 10.0.1.0

The next step is to configure the address pool on the DHCP router that is available through the command shown below.

Figure 8.127 Define an address pool

The pool name is DHCP and the network whose addresses will be assigned dynamically is 10.0.1.0/24 . Now you need to specify the rest of the information for this DHCP pool, that is: default gateway, DNS server (optional, not applicable to this example, but we will show the command) and IP domain (also not applicable to this example, but we will show the command):

Figure 8.128 Define the default gateway, DNS server, and domain Now you need to configure IP addresses that should not be assigned automatically (e.g. to be reserved as statically reserved addresses for servers). In this command we provide a list of addresses (in our case it is a range from 10.0.1.10 to 10.0.1.20 inclusive):

Figure 8.129 Exclude addresses from the pool

If we now connected any device with a configured network adapter to dynamically receive an IP address, it would be assigned, provided that the router adapter is configured to the default gateway address of this pool. In this example, you notice that no end device is directly connected to the DHCP router that serves as the DHCP server. The router does not know what to do with it after receiving a DHCP query because it does not know where the DHCP server is located.

Figure 8.130 DHCP server information is missing

In order for the router to know where to send the DHCP query, a command indicating the address of the DHCP server should be configured on the interface where it receives DHCP queries.

Figure 8.131 Provide DHCP server information

From the router' s perspective, the DHCP server address is 10.0.0.2, which is why we provide this address. When we now try to ask for a dynamic IP address, the router will send this command further, i.e. to the address 10.0.0.2.

Figure 8.132 Positive result of a dynamic address query from the DHCP server

8.3.7 Static Routing Configuration

Static routing is a manual indication of the way to a different network on each router separately. Since this is not dynamic routing, if there is any change in the network, it will not be noted on any other router except the one on which the change occurred. In this example, static routing will be configured manually and as in the case of configuration through the graphical interface it was possible to indicate only Next hop or the address of the next jump, so in this case you will be able to enter either Next hop IP address or the output interface from which the packets are to be routed. An example of a static routing configuration will be discussed on the following topology, consisting of five routers through which PC1 and PC2 will send information to each other.

Figure 8.133 Topology for static routing configuration

In accordance with the assumptions and the topology designed by us, we will now configure the route with which the packets will be transmitted. Let's assume that network traffic starts from PC1 and leads along the shortest route, through routers: Router1→Router2→Router4 → Router 5 , up to PC2. This route is marked in red in the figure below. Of course, before configuring static routing, we need to configure all interfaces, i.e. assign them IP addresses and enable them (or define the appropriate Clock Rate value). Static routing is configured in global configuration mode via the following command.

ip route [destination network address][target network mask][name of the output interface through which data or IP address of the intermediate router will be sent] In the case of the way back (from PC2 to PC1) it will be the way through routers: Router 5 → Router 4 → Router 3 → Router 2 → Router 1 as shown in the figure below in blue.

Figure 8.134 Direction of movement of packets

We start by configuring static routing on Router1 and Router2 as shown in the figures below.

Figure 8.135 Static Routing Entry - Router 1

Figure 8.136 Static Routing Entry - Router 2

Figure 8.137 Static Routing Entry - Router 4

Figure 8.138 Static Routing Entry - Router 5

We do not need to configure two entries on Router1 and Router5 , because these routers know where their local networks are located. After PING checking the communication between computers, we should see on the simulation where the packets are going.

Figure 8.139 Positive PING from PC2 to PC1

Figure 8.140 The route of the packages

As we can conclude from the packet run, the configuration agrees with our assumption and in this way we have configured static routing. However, static routing is not the best idea for implementing network configuration, because it requires a very large amount of work from the network administrator and does not adapt to changes in the network and is prone to administrator errors. Dynamic routing protocols, on the other hand, when properly selected and configured, are characterized by greater flexibility. In addition, one important piece of information. It is worth having one static entry on the router, which is called the default route or literally referred to as a phrase translated from English ( Gateway of last resort ). It is used when the packet does not find the destination network in the routing table.

Figure 8.141 Gate of last chance - static entry

The last chance gateway determines to which interface or IP address (depending on which entry we make) all packets whose target network is not in the routing table entries of a given router will be directed. To execute this entry, use the command: ip route 0.0.0.0 0.0.0.0 <interface number > or <IP address>

8.3.8 RIP Routing Protocol Configuration

The configuration of the interfaces on the routers alone is not enough for them to be able to transmit information from one network to another, for this purpose it will be necessary to configure one of the routing protocols. In our case, we will get to know the simplest one, i.e. RIP, and then EIGRP and OSPF. The following figure shows the topology that you will need to learn how to configure a routing protocol.

 Configuring Cisco Routers

Figure 8.142 Topology for RIP routing protocol configuration After completing the topology, you can proceed to configure the IP addresses of the router interfaces. After configuring IP addressing and enabling all interfaces, the LEDs should light up green, however, the network still does not work. To do this, we must inform each router about the network addresses bordering it. Each router borders three different networks, for example, Router2 with networks: 10.0.0.0; 30.0.0.0 ; and 40.0.0.0.

Figure 8.143 Initial configuration of interfaces before implementing RIP To access the protocol configuration, from the global configuration, go to the RIP configuration level using the RIP router command, as shown in the figure below. The first version 2 command is a command that was not available in the GUI and that activates the second version of RIP . The difference between the first and second versions is that the first version only takes into account class addresses and could not be used in the above topology due to the fact that we have created different networks there that have non-class addresses and the router could not broadcast these individual networks. For example, Router 2, instead of broadcasting three networks: 10.0.0.0, 10.0.0.4 and 10.0.0.8 , would broadcast only one network: 10.0.0.0 , which would not allow the network to work properly. Therefore, it is recommended that you always use the second version of the RIP routing protocol (each subsequent newer version of the routing protocol already automatically distinguishes between network addresses).

The next no auto-summary command is a command that does not allow the router to sum up networks and broadcast rasterized networks. An example would also be Router 2, which instead of broadcasting networks 10.0.0.0, 10.0.0.4 and 10.0.0.8 would only announce that a 10.0.0.0 network is available through its interfaces. Further commands are already known and they apply to neighboring networks.

Figure 8.144 RIP Configuration - Router 1

Figure 8.145 RIP Configuration - Router 2

Similarly, we configure the remaining routers and after some time (you have to wait a while so that the routers have time to broadcast their networks) and check, for example, on Router 4 what its routing table looks like.

 Configuring Cisco Routers

Figure 8.146 Routing Table - Router 2

All networks have been properly advertised and we can find a way to each network in our topology. Let's check which way the packets will travel between computers.

Figure 8.147 RIP - route from PC1 to PC0

 Configuring Cisco Routers

Figure 8.148 RIP - RIP - route from PC1 to PC2

The RIP protocol works as it should - it chooses the route with the least number of jumps to the destination

8.3.9 EIGRP Routing Protocol Configuration

The second dynamic routing protocol is EIGRP ( Enhanced Interior Gateway Routing Protocol ) is a Cisco-designed, enhanced version of IGRP. This is the first routing protocol that works according to the link state, and not as in the case of RIP - using a distance vector. The difference is that EIGRP takes cost into account from source to goal – it has a more complicated metric. The most important thing you need to know now is that the metric consists of the bandwidth of links along the way and the delay that will be imposed on the packets. The advantage of this protocol is that EIGRP does not send periodic updates. Instead, it refreshes neighborhood relationships with nearby routers by sending small packets and sends partial updates when it detects changes in the network topology. Therefore, it consumes far less time and bandwidth than distance vector (RIP) protocols. The topology used to configure EIGRP will be similar to the previous one, but in this case we will increase the bandwidth of serial links (4Mbps).

 Configuring Cisco Routers

Figure 8.149 Topology for EIGRP routing protocol configuration We start EIGRP protocol configurations in a similar way (provided that we have already addressed all interfaces) using the router eigrp <AS> , command, where we enter the autonomous system number instead. An autonomous system is a collection of devices that are under common administrative control, in which a consistent routing scheme is maintained. This protocol provides for the creation of from 1 to 65535 different autonomous systems connected to each other. In the example, it will be an autonomous system 1.

Figure 8.150 Entry into EIGRP 1 configuration mode

In the case of EIGRP, we do not choose any version of this protocol, but we can immediately enter networks adjacent to the router. After specifying the network address, specify the inverted network mask as shown in the figure below.

Figure 8.151 Configuring EIGRP 1 on Router A

An additional command that can be used is no auto-summary , which we discussed earlier and it is worth using them so that no misunderstandings happen.

 Configuring Cisco Routers

Figure 8.152 Configuring EIGRP1 on Router B

After configuring the neighbouring router to the one we configured at the very beginning, we will get a notification Neighbor 10.0.0.1 is up: new adjacency . This is a message that the EIGRP on both routers has been properly configured and they could set up a connection with each other - exchange information about routes. Similarly, let's configure the other routers and try to display the routing tables on Router C.

Figure 8.153 Routing Table - Router C

We see that all routes have been well advertised and the router has calculated the fastest route to each network. In square brackets in red is marked an example of a metric that the router calculated for a given network - the smaller the better the route to the destination. Let's run the connection test again. Let's start with the command PING from PC1 to PC0, and then from PC1 to PC2.

 Configuring Cisco Routers

Figure 8.154 PING from PC1 to PC0

Figure 8.155 PING from PC1 to PC2

8.3.10 OSPF Routing Protocol Configuration

OSPF (Open Shortest Path First) is the third and final dynamic routing protocol to be described. It is also a link state protocol, that is, it does not choose the path to the destination based on the smallest number of jumps but on the basis of complex mathematical calculations.

Routing using OSPF is based on autonomous systems (AS) in the same way as EIGRP, but with the difference that in the OSPF protocol autonomous systems are still divided into areas (so-called areas). The specificity of the OSPF algorithm and the amount of resources it consumes mean that the group should not have more than 50 routers in one area. In networks where there are regular link failures, frequent recalculations are necessary – in such networks small areas should

The maximum number of AS (i.e. the number of so-called OSFP processes ) is 65535, and area numbers can be defined theoretically in the range from 0 to 4294967295. We will start the configuration based on the same topology that you created in the previous section so that you can see the differences in the different routing protocols.

Figure 8.156 Topology for OSPF routing protocol configuration After you configure IP addresses and interfaces, you must configure the routing protocol. Again, our autonomous AS system will be equal to 1 , and the area (which must be taken into account when entering neighbouring networks) will have the number 0 . In the case of OSPF configuration, it is worth giving each router its own router-id number, which facilitates communication between routers and building the OSPF database.

Figure 8.157 Configuring OSPF1 - ROUTER 1

Figure 8.158 Configuring OSPF1 - ROUTER 2

As in the case of EIGRP, OSPF displays a message stating that two routers have communicated with each other and replaced their routing tables and set up a connection, but in this case it is not the IP address of the neighbor router, but its router-id. After the analogous configuration of the rest of the network devices, we can go to the commands verifying the correctness of the configuration.

Figure 8.159 Command show ip ospf neighbor

The command to verify the correctness of the configuration is show ip ospf neighbor , which shows us neighbouring routers that are also involved in broadcasting routes using the OSPF protocol. In the first column ( Neighbor ID ) there are IDs of routers that have been assigned by us (if we did not give it, the router would choose the router-id , which would usually be equal to the smallest IP address on its interfaces). The third column ( State ) shows the current status of the neighbouring router. The inscription FULL means that the router has finished the initial communication, has exchanged networks and is ready to work. In the fourth column ( Dead Time ) there is a time left to exchange subsequent packets, which will be counted down every 1 second. If this time passes and these packets are not exchanged between the two neighbours, the connection will cease to exist and the routers will no longer be able to communicate with each other using OSPF . The last two items refer to the nearest IP addresses and interfaces from which adjacent routers are accessible.

Figure 8.160 Command show ip route - OSPF

The show ip route command displays the current routing table of the router. The designation for routes obtained through the OSPF protocol is the letter O placed in the first column. In square brackets, a pair of values [ administrative distance/metric ] is placed. The administrative distance for OSPF is always 110 as standard, while the metric is calculated using a special algorithm and its value depends on the current state of the entire network. You can now perform the test using the PING command from PC1 to PC0 and from PC1 to PC2.

Figure 8.161 PING from PC1 to PC0

Figure 8.162 PING from PC1 to PC2

Based on the test performed, the route chosen by the OSPF protocol is the route going from the source (PC1) to the destination (PC0), through routers: ROUTER1, ROUTER2, ROUTER6, ROUTER7 , but if the network changes parameters such as link bitrate, overstatement or underestimation of the contractual cost of the link, then the route set by OSPF may be different.

Final remark. OSPF is widely used in WANs, but RIP is not. On the other hand, the RIP protocol, due to its limitations (the maximum number of jumps is 15, it heavily loads network resources and routers, and thus slows down the operation of the network) can be optionally used in very small local networks and most often, only for educational purposes (its advantage is the simplicity of configuration).

8.3.11 Local Definition of Router Names

When the network is working properly, i.e. the IP addresses of the devices have been properly configured and the routing protocol has been selected and configured, and all devices can communicate via IP addresses, we will describe how to introduce the possibility of communicating via names instead of IP addresses. Assumed that the devices are connected as follows, as shown in the figure below.

Figure 8.163 Topology to show the operation of the ip host command The three routers were named as follows: ALFA, BETA, GAMMA , which, however, will not affect the operation of the network itself, but will only introduce some order in the topology.

In order to allow routers to communicate with each other using a name system, enter the names of the routers and all their IP addresses assigned to the interfaces into the configuration. You can not forget to enter this type of information also about neighbouring routers.

For each router, enter three configuration lines in global configuration mode, starting with the ip host command, then specifying its name and all IP addresses that are assigned to the router, as shown in the following drawings.

Figure 8.164 ALFA router configuration - ip host

Figure 8.165 BETA router configuration - ip host

Figure 8.166 GAMMA router configuration - ip host

In order to test the performed configuration, you need to PING the ALFA router to the BETA router (this should be done from the privileged mode), but instead of the IP address of the destination host, you must specify its name – in this case it will be: ping BETA . After a while, we will receive a response confirming the success of PING packet delivery, as shown in the figure below.

Figure 8.167 Attempt to send PING from ALFA router to BETA router In the event that the IP HOST configuration went incorrectly, then when you try to refer to the destination host by its name, you receive the following message, shown in the following figure.

Figure 8.168 No response to the PING command using the host name

8.3.12 Save the Current Configuration

When working with hardware (real and simulated in the Cisco Packet Tracer), experience teaches us how easy it is to lose configurations that took us many minutes and sometimes many hours to create, all you need to do is turn off the power of the device, or other events such as hanging or failure of the Cisco Packet Tracer program. Therefore, at the beginning of each chapter there is a warning informing that during the performance of exercises or control tasks / project / periodically save the state of the file (keyboard shortcut Ctrl + S ). This section describes how you can protect your router configuration from accidental power off. By default, the configuration is saved in RAM, which is volatile memory. Therefore, it is worth remembering about the possibility of saving it in NVRAM ( non-volatile random-access memory ), which is a non-volatile memory. Once the device is fully configured and has passed the necessary performance tests, we can proceed to save the configuration. For this purpose, we will use the topology, which is illustrated in the figure below.

Figure 8.169 Sample topology showing how to save the current configuration The contents of the current configuration are displayed through the command: show running-config , which must be typed in privileged mode. A fragment of the router configuration from the described topology is shown in the figure below.

 Configuring Cisco Routers

Figure 8.170 Fragment running-config

This configuration is not saved permanently, it is valid as long as the device is turned on, i.e. until the power is turned off in the device. Therefore, the configuration should be stored in NVRAM non-volatile memory.

To check what has been saved in the NVRAM memory of the router, just run the command: show startup-config (also in privileged mode). When we have a router in which nothing has ever been saved in NVRAM before or its contents have been cleared, then the router will display a message:

Figure 8.171 Effect of trying to display a non-existent config If you want to copy the current configuration to the startup configuration, just execute the command (in privileged mode): copy running-config startup-config , after pressing the Enter key, you will be asked in which file it should be saved. By default, this is the startup-config file, which is confirmed again by pressing the Enter key. The following message will then be displayed:  Configuring Cisco Routers

Figure 8.172 Copy the current configuration to the startup configuration Note for Advanced Cisco Packet Tracer Users .

In most routers, instead of the copy running-config startup-config command, you can use another command, e.g. write or shortcut w , but this remark does not apply to real CISCO devices . On the other hand, in multilayer switches or ASA devices, instead of the copy running-config startup-config command, you can use the write memory command or the shortcut w m .. The above method allows you to significantly shorten the time of testing and performing device configuration. After you copy the current configuration to the startup configuration, you can turn off the power to the router because the configuration has been properly secured. In the event that incorrect information has been saved in the startup configuration and it is required to delete it, you can delete the startup configuration at any time using the command: erase startup-config . After entering the command, it is required to confirm the decision using the Enter key.

Figure 8.173 Delete a startup configuration

8.3.13 Securing Your Configuration

Often, when working with CISCO devices, it happens that you need to test some new configuration or implement other settings. You do not need to perform many manual configurations, but you can use the configuration that we previously saved on the Trivial File Transfer Protocol ( TFTP ) server. TFTP is a simple protocol used to transfer files that cannot display directories or authenticate users, and its only purpose is to transfer files to or from a computer. TFTP is a simplified version of FTP service. A TFTP transmission begins with a request to read or write a file, which also requests a connection. The file is sent in blocks from 0 to 512 bytes in length. A data packet of less than 512 bytes indicates the end of the transfer.

To illustrate this possibility, we will use the topology shown in the figure below.

Figure 8.174 Topology for device configuration security

The LAN (20.0.0.0 ) that is connected to the router hosts a server on which you can configure the TFTP service, which will be used to store the router configuration. To do this, go to the server, open the Services tab, and then enter the TFTP section. Due to the fact that the TFTP service is a simplified version of FTP, you do not need to configure anything here, you just need to make sure that it is attached, as shown in the figure below. In the File window, there are already files that are on the server, these are images of IOS systems that will not bother us. Therefore, after switching on the service, we can leave the server configuration and return to the router.

Figure 8.175 Configure the TFTP service on the server

Copying the configuration to the TFTP server is done in privileged mode using the copy running-config tftp command. After some time, you will be asked for the server address. This is the IP address of the TFTP server. In our case, it will be 20.0.0.2 . The next question concerns the name under which the file should be stored on the TFTP server. The router suggests the name Main_router-confg , if we agree to it, press Enter or type a new file name. After the configuration is saved correctly, you should see the message as in the figure below.

Figure 8.176 Successful attempt to copy the configuration to the server You can check if the file with the saved configuration exists on the TFTP server.

Figure 8.177 Copied file on TFTP server

How can i restore a saved configuration, i.e. copy it from the TFTP server to the startup configuration? To do this, execute the copy tftp startup-config command. You will be asked for the server address and file name to copy.

 Configuring Cisco Routers

Figure 8.178 Steps to copy a configuration from a TFTP server to a startup configuration

9 Configuring Cisco Switches

The chapter covers basic theoretical and practical knowledge of configuring simulated switches in the Cisco Packet Tracer.

9.1 Exploring the Equipment of Cisco Switches Another type of devices available in the program are switches . We have at our disposal three basic switches that are equivalent to real models from the 2950 to 2960 series, models called PT-Switch and PT-Empty , which can be modified in any way, as well as third layer switches 3560 , 3650 and IE 2000 .

Figure 9.1 Switch models available in the Cisco Packet Tracer Unlike routers, each of which had the ability to install optional modules, in the case of switches, only PT models allow the replacement of modules. Other devices do not allow you to change their equipment.

9.1.1 Switch 2950

The first switch we will discuss is the 2950 series switch. It is a manageable device dedicated to small and medium-sized networks. It has 24 Fast Ethernet interfaces with a bandwidth of 10/100 Mbps.

Figure 9.2 Physical appearance of the 2950 series switch

The 2950 Series Switch does not support any optional equipment.

9.1.2 Switch 2950T

Another switch available in the program is the 2950T series switch. This switch is a managed device dedicated to a medium-sized network. It has 24 Fast Ethernet interfaces with a bandwidth of 10/100 Mbps, as well as two Gigabit Ethernet interfaces with a bandwidth of 10/100/1000 Mbps.

Figure 9.3 Physical appearance of the 2950T series switch

The 2950T Series Switch does not support any optional equipment.

9.1.3 Switch 2960

Another switch available in the program is the 2960 series model. It is a manageable device dedicated to medium-sized networks. It has 24 Fast Ethernet interfaces with a bandwidth of 10/100 Mbps, as well as two Gigabit Ethernet interfaces with a bandwidth of 10/100/1000 Mbps similar to the switch version 2950.

Figure 9.4 Physical appearance of the 2960 series switch

The 2960 Series Switch does not support any optional equipment.

9.1.4 PT-Switch and PT-Empty Switch

The next switches available in the program are the two PT series switches, which are devices only found in the PT program, but allow you to create many different hardware configurations. They have ten slots, in the place of which we can mount the selected interface. When adding this switch to the topology, there are two versions to choose from: PT-Switch and PT-Empty . These switches also have power switches. The first of them by default has four Fast Ethernet ports with a bandwidth of 10/100 Mbps, using twisted pair cables and two Fast Ethernet interfaces with a bandwidth of 10/100 Mbps in the fiber optic standard and two free slots. The second is a completely empty version, without mounted modules.

Figure 9.5 Physical appearance of the PT-Empty switch

In free slots we can install the following components:

Figure 9.6 PT Switch Optional Equipment

Below is a detailed description of the individual components:

 PT-SWITCH-NM-1CE - a single Ethernet port with a

bandwidth of 10 Mbps,

 PT-SWITCH-NM-1CFE - single Fast Ethernet port with a bandwidth of 10/100 Mbps,

 PT-SWITCH-NM-1CGE - single Gigabit Ethernet port with 10/100/1000 Mbps bandwidth,

 PT-SWITCH-NM-1FFE - single Fast Ethernet port with a bandwidth of 10/100 Mbps in the fiber optic standard,

Ethernet port in fiber optic standard.

 PT-SWITCH-NM-COVER - module for protecting the inside of the switch

9.1.5 Series 3560

Another switch available in the program is the 3560 series switch. It is a so-called multi-layer switch, which means that it has wider possibilities compared to other switches, because it works not only in the second ISO / OSI layer, but also in the third layer (in the same as routers). It has 24 Fast Ethernet interfaces with a bandwidth of 10/100 Mbps, as well as two Gigabit Ethernet interfaces with a bandwidth of 10/100/1000 Mbps.

Figure 9.7 Physical appearance of the 3560 series switch

The 3560 Series Switch does not support any optional equipment.

9.1.6 Series IE 2000

The IE 2000 ( Industrial Ethernet 2000 Series ) switch is an industrial switch that simulates a 2000 series switch model. The switch is running IOS IE2000 Software (IE2000-UNIVERSALK9-M), version 15.2(1)EY . The switch meets the requirements of industrial networks for speed of convergence and security.

Figure 9.8 Physical appearance of the IE 2000 series switch The switch has 8 Fast Ethernet interfaces and 2 Gigabit Ehternet interfaces. Supports Resilient Ethernet Protocol ( REP ).

9.2 Configure Cisco Switches Using the Graphical Interface

9.2.1 Interface Configuration

At the beginning we will create a simple topology consisting of four computers and one switch.

Figure 9.9 Topology for switch configuration

As we already know, when we address these computers now (for example, so that they are in the network 192.168.0.0/24), they will be able to communicate with each other without any problem as shown in the figure below – despite the fact that the configuration of the switch remained the default.

Figure 9.10 PING between devices

Now that we are sure that with the default configuration our network works seamlessly, we can go to the Config tab on the switch and see what options the configuration offers us using the GUI.

Figure 9.11 Switch Config tab

As you can see, we do not have too many options to choose from - configuration of basic settings such as the name of the switch or saving the current configuration, then there is Algorithm Settings - not the option we are interested in, VLAN database and configuration of the interfaces themselves. Let's take a look at the interface configuration at the beginning.

Figure 9.12 Switch Interface Configuration - GUI

We have at our disposal enabling / disabling the interface, with what bandwidth a given port works, what duplex it supports and what VLAN belongs to and in what mode the port is located (we have a choice of Access or Trunk mode, as in the figure below).

Figure 9.13 Selecting the port mode

The difference in the operation of these modes is described below:

 Access - if the port is in this mode, the switch usually accepts all untagged frames from this port and gives them a predefined tag - depends on which VLAN the port is located in. If data is to be sent to a port that is in this mode, the tag is removed. Most often, access mode is used on ports to which end users are attached, e.g. desktops, laptops, printers.

 Trunk - a port through which information from all VLANs can be sent by default. In this port pass frames that are tamed and usually ports of this type connect two switches, or a switch to the router.

Tagging frames involves adding an additional field (VLAN tag) containing the VLAN number to them. In this example, the ports work in the default Access mode.

9.2.2 Configuring Virtual LANs (VLANs)

What is a VLAN (Virtual LAN) and how do I configure it? This is one of the most useful functions of switches that we can configure, so it is worth getting to know this issue and mastering it as much as possible.

As the name suggests, these are LANs, but separated from each other virtually, not physically. For example – in a residential building we have many LANs, as a standard each apartment is a separate LAN, and in the case of VLANs we can virtually divide one apartment into smaller LANs that cannot communicate with each other without the participation of a router.

To illustrate the division of LANs into VLANs, we will use the same topology that was presented a moment ago, but we will divide it in the diagram into two separate VLANs: VLAN10 and VLAN20 .

Figure 9.14 Topology for VLAN configuration (Example 9.2.2a.pkt) Now you need to configure VLANs on the switch. In the Config tab, go to the VLAN Database . There we need to add two VLANs that interest us: number 10 and number 20 with the names VLAN10 and VLAN20 . respectively.

VLAN number 1 is the default VLAN and includes all ports before the switch is configured.

Figure 9.15 Adding new VLANs using the GUI

The next and last step is to configure the ports in such a way that they work in Access mode and belong to the appropriate VLANs.

Figure 9.16 Assigning VLAN to the appropriate interface - VLAN10

Figure 9.17 Assigning VLAN to the appropriate interface - VLAN20 Similarly, we assign the other two interfaces to the respective ports. We can now test whether we are able to communicate in the area of one VLAN and whether we are able to connect to a computer located in another VLAN.

Figure 9.18 Test of communication in VLAN and between VLANs As we might have expected - communication in the area of one VLAN is possible as if nothing has changed since the previous attempt, but communication between VLANs is blocked.

To illustrate how the port that is in Trunk mode works, we will add to our topology one more switch, connected to the first via optical fiber, and two additional computers located in VLAN10 and VLAN30 .

Figure 9.19 Topology with two switches to configure trunk connection (Example

9.2.2b.pkt)

After properly addressing two additional computers, we will configure the Trunk connection on the Switch 1 .

Figure 9.20 Trunk - Switch Connection Configuration 1

When you select trunk on the appropriate interface, all existing VLANs on the switch are automatically assigned to this port. We proceed to the configuration of Switch 2 . We first create a database of VLANs - VLAN10 and VLAN30 , and then assign them to ports operating in Access mode.

Figure 9.21 Port assignment to the corresponding VLAN - VLAN30 The second port leading to PC6, but assigned to VLAN10, should look similar. Now let's deal with the connection to The Switch 1 . Let's set this port as a Trunk port and try to achieve communication between PC6 and PC1.

Figure 9.22 Trunk Connection Configuration - Switch 2

Figure 9.23 Communication between PC6 and PC1

Everything works as it should, but when we try to communicate between VLANs again, we will not achieve a positive result, because we have not configured any router that would allow it.

Figure 9.24 Communication between VLANs

9.2.3 Enabling Communication Between VLANs

To enable communication between different virtual networks that have been created on switches, you need to add a router to our topology and connect it to one of the switches, for example the Switch 2 , and configure the router with a function that we have already discussed – the so-called sub-interfaces. If we did not do this, we would have to create one connection between the switch and the router for each existing VLAN, which is neither practical nor simpler.

The topology that we will use to show how routing between VLANs works will look similar to the previous ones, but we will attach the router to the Switch 2 and change the network addressing. Now each VLAN will have its own part of the 192.168.0.0/16 network due to the fact that you have to specify different default gateways on computers. The first available network address will be the default gateway address, e.g. for the

192.168.10.0/24 network it will be 192.168.10.1.

Figure 9.25 Topology for configuring Router on a stick (Example 9.2.3.pkt) The first step to configure routing between virtual networks is to configure the switches themselves – you need to agree on vlan databases so that both switches have the same VLANs. This will be needed later due to the fact that on trunk links on both sides must be configured permission to move the same VLANs.

Figure 9.26 VLAN Database - Switch 1 and Switch 2

When the VLAN base agrees on both switches, Trunk connections should also be allowed to move the same VLANs from two sides (on Switch 1 and on Switch 2 ). It's time to switch to Switch 2 and set up one more Trunk connection – between the switch and the router.

Figure 9.27 Setting up another Trunk - Switch 2 connection We can now configure the Interface of the Fa0/0 router using commands to create three sub-interfaces – one for each existing VLAN. The next step is to execute the appropriate command on each encapsulation dot1q <VLAN number > (thanks to which the router will know how to mark, i.e. tag each frame from a given sub-interface) and assign the appropriate IP addresses for each sub-interface as shown in the figure below.

Figure 9.28 Configuring Router-on-a-stick

It remained for us to carry out tests of communication between VLANs. Through the configuration process, we could already understand how the idea of Router on a stick works, in which the router is the default gateway for each VLAN and it is he who performs routing between VLANs. Until this router is included in the network, VLANs cannot communicate with each other.

Figure 9.29 Traffic from VLAN10 to VLAN30

The figure above shows how the communication between VLANs looks like. Using the PING commands, you can confirm the path traveled by the packet, which is shown in the figure below.

Figure 9.30 PING between VLAN10 and VLAN30

Figure 9.31 PING between VLAN20 and VLAN10

9.3 Configuring Cisco Switches in the IOS

9.3.1 Basic Information

In order to start configuring the switch in a real environment, you will need to have any computer with a COM port ( RS232 ), a console cable and, of course, the switch itself. We connect the computer to the switch in the same way as in the case of a router, so we will not describe it here again.

Figure 9.32 Correct console connection

The connection to the switch is established in the same way as in the case of a router, using the Terminal application. In the configuration window that appears after starting Terminal , do not change any parameters and click OK .

Figure 9.33 Correctly log into the switch

9.3.2 Basic Switch Configuration Modes

Unlike routers, switches do not have a wizard mode, so they must be configured only manually. Basic functions such as navigating the console, using help, and even checking the status of the device look analogous to routers, so they will not be described again.

9.3.3 Interface Configuration

The configuration of a given interface is analogous to the configuration of the interface in a router. First, we go into the global configuration mode, and then using the interface command interface <type><number> we configure the interface. You can change the port bandwidth using the command speed <bandwidth of Mb/s> .

Figure 9.34 Change interface bandwidth

Another interface parameter that we can configure is duplex mode. The mode is set with the command duplex <mode> , where the available modes are: full, half and auto .

Figure 9.35 Changing the duplex mode of the interface

Another option is to configure the interface to use VLANs. If the interface is to be in Access mode and only one VLAN is to belong to it, we use the switchport mode access command to set the interface mode to access , and then assign the interface to a specific VLAN with the switchport access VLAN command switchport access vlan [number] . On the other hand, if the interface is to work in trunk mode, instead of the two previous commands, enter switchport mode trunk . How to use these commands is described in the chapter on VLAN configuration. To assign VLANs to the Trunk port we use the switchport trunk allowed vlan command switchport trunk allowed vlan [all or VLAN number] ,, of course the default option is all.

Figure 9.36 Changing the mode of operation of ports and assigning VLANs

9.3.4 VLAN Configuration

We will start by creating the following topology, on the example of which we will configure VLANs:

Figure 9.37 Topology for switch configuration (Example 9.3.4.pkt) As you can see, the topology predicts the existence of three VLANs – VLAN 10, VLAN 20 and VLAN 30. So we'll start by creating them on the switches. To create a VLAN, we must first enter the global configuration mode and use the command with the syntax: vlan [number] .. We can then name the virtual network by using the name command. We return to the global configuration mode with the exit command, and then create the second necessary VLAN and the third. Repeat on the second switch as well.

Figure 9.38 Create VLANs on the switch

If we do not give VLAN a name, it will get the default name, in the above case it would be VLAN0010. VLANs can also be deleted, we do this by typing the command no vlan [number] in the global configuration mode. Now let's check if the corresponding VLANs have been created correctly. To do this, we need to enter privileged mode and then use the show vlan command.

Figure 9.39 Show vlan command on a switch

We can find here information about VLANs that were created on the switch and what ports are assigned to the VLAN data. We will start by assigning those interfaces that connect computers to the switch. So we enter the global configuration mode, and then the interface, in the way already described above. These interfaces belong to individual VLANs and connect to end devices, so they will work in Access mode.

Figure 9.40 Changing the operating modes on the switch interfaces Similarly, it should look on the second switch with the corresponding change of interfaces. Next, proceed to change the operating mode of the interface, connecting both switches. It connects two network devices and will transmit data from several VLANs, so it will work in Trunk mode.

Figure 9.41 Change the interface mode to Trunk

To perform connection tests between once whether computers in the same VLANs can communicate with each other.

Figure 9.42 PING between VLANs

9.3.5 Configuration of Virtual Terminals (Telnet, SSH)

In the case of switches, as for routers, they can be configured remotely from LAN or even VAN via virtual terminals such as Telnet or SSH . Now let's create the following topology.

Figure 9.43 Topology to configure remote configuration

T o co nf igu r e a s w itc h to con ne c t to it v ia T e ln e t or S SH , you must first give it an IP address so that it is visible on the network. Configure the VLAN1 interface and give it an IP address, e.g. 192.168.0.254/24 .

Figure 9.44 Giving an IP address for VLAN 1

After such a configuration, computers in the topology will be able to communicate with the switch, e.g. using the PING command, however, if we try to connect to it using Telnet, we will receive the message Connection to 192.168.0.254 closed by foreign host , as you can see in the figure below.

Figure 9.45 Attempt to communicate with a switch

To connect to the switch, we must enable the ability to remotely connect via Telnet, as well as enable authorization by setting a password. We do it in the same way as on a router.

Figure 9.46 Activating switch access using virtual terminals Now we are able to connect to the switch using the Telnet protocol:

Figure 9.47 Positive attempt to access the switch using the Telnet protocol Once we have access via Telnet, we can configure a more secure connection – a connection using the SSH protocol. To do this, you need to rename the switch (due to the fact that Switch is the default name of the switch and SSH is a secured protocol, so it does not allow default values for names, among other things). After that, configure the IP domain and generate RSA keys, which are already described in the section on configuring SSH access to the router.

Figure 9.48 Configure SSH switch access

You must also create a user (login and password) to which you will be able to log in.

Figure 9.49 Create a user on a switch

Next, you need to perform permission on the switch for SSH connections.

Figure 9.50 Permission for internal SSH connections

Now you need to perform a login test (access using SSH) from the computer to the switch.

Figure 9.51 SSH access to the switch

9.3.6 REP Protocol

Cisco RESILIENT Ethernet Protocol ( Cisco REP ) is a Cisco protocol used in networks known as Carrier Ethernet . Carrier Ethernet is a technology used to build large WAN structures based on the Ethernet standard. This technology allows ISR providers and operators to build large-area, multi-branch corporate networks to provide standardized services. The primary goals of Carrier Ethernet are standardization, scalability, management, reliability, and quality of service.

The main features of the REP protocol are:

 the protocol is owned by Cisco,

 it is mainly used in Metro Ethernet networks based on ring topology,

 it allows you to prevent the formation of a second layer loop,

 it is faster than the STP protocol, it can provide short network convergence times (about 50 mS – 150 mS).

9.3.6.1 Purpose of REP

The main purpose of REP is to prevent Layer 2 loops in physical and logical topologies of the following types:

 point-to-point,

 star,

 bus,

 ring.

9.3.6.2 Basic Concepts of REP

REP segment – a chain of ports connected to each other and marked (configured) with one and the same identifier, the so-called segment ID . The ID segment is an integer from 1 d o1024.

A REP edge switch is a switch located at the edge of a REP segment. Edge port of the REP segment (edge port) – a port of the edge switch , located inside the REP segment.

Figure 9.52 An example of a REP segment in a point-to-point topology.

Figure 9.53 An example of a REP segment in a point-to-point topology.

Figure 9.54 Sample REP segment in Ring topology

Setting up a REP segment is very simple. On each of the ports inside the REP segment, use the following commands:

SW1 (config-if)# sw mod trunk

SW1 (config-if)# rep segment N

where N is an integer between 1 and 1024 , denoting the segment ID. On each switch, execute the following commands.

en

conf t

interface fa1/1

sw mod trunk

rep segment 1

interface fa1/2

sw mod trunk

rep segment 1

physical topology in the Cisco Packet Tracer.

Physical topologies are used to illustrate how network equipment has been deployed in rooms, buildings, housing estates, etc. It shows the actual wiring process, taking into account, among others, such factors as: distance between devices, wireless network coverage or length of cables connecting given devices. Before you describe physical topologies in detail, you must create a logical topology, along with a description of the buildings. In this example, this is the following logical topology, which will be used further as the basis for creating a physical topology.

Figure 10.1 Example logical topology

The assumptions necessary to create a physical topology are:

 Buildings 1 to 4 are located in city A, while building 5 is located in city B.

 Connections between buildings will use optical fibres.

To create a physical topology, start by switching the program to Physical mode. To do this, click the icon in the upper-left corner of the workspace. In the same place, you can return to logical topology design mode at any time. You can also use the keyboard shortcuts Shift + P for physical topology and Shift + L for logical topology.

Figure 10.2 Switch to physical view

When you switch to Physical mode, the physical topology design mode appears. We have four types of locations at our disposal where we can place devices. These are: Intercity (the largest area, covering the entire working area), City (city), Building (building), Wiring Closet (rack cabinet with equipment, i.e. e.g. the main distribution point or intermediate distribution point).

It is not a tool for advanced structural network designers, but it is suitable for teaching the basics of network design, for example, for creating basic network designs (mainly for educational purposes). An example of a physical network project is described in a separate chapter. Physical devices form a kind of hierarchy – the main area contains cities, cities contain buildings, buildings contain devices, etc. However, it is not necessary to accept this hierarchy as binding, it is possible to place a given device, for example, directly in the city.

By default, each topology contains one city, one building in it, and as many stations in the building as needed to accommodate all the equipment.

 Physical Topology in the Cisco Packet Tracer

Figure 10.3 Program window in Physical mode

You can zoom in and out of the physical topology view as you see fit using the magnifying glass icons in the top bar. In physical topology, you can move in two ways. The first is to click the mouse on the location of the object in question, which can be opened. To return one level higher, use the Back button on the navigation bar at the top.

Figure 10.4 Navigation bar

The navigation bar shows the name of the location that is currently open. The second way to navigate the physical topology is to click the NAVIGATION button. A list of all existing locations opens.

Figure 10.5 Intercity locations

 Physical Topology in the Cisco Packet Tracer

Figure 10.6 Window with a list of existing locations

The list is presented in the form of a table. On the left there are the names of the locations along with their location in the hierarchy. We can also collapse specific fragments. On the right, however, you can see the types of locations – City , Building , Device , Wardrobe ( Wiring Closet ). To move to any of them, click on it, and then on the Jump to Selected Location button.

The appearance of the stations with the equipment is significantly different from the view of the city or building, because it shows the physical appearance of the equipment, along with such elements as diodes and interfaces. The equipment can be located in rack cabinets (devices such as routers, switches, access points or servers) or on tables (devices such as computers, laptops or tablets).

Each station can contain a maximum of three cabinets or tables, which means that the number of devices it can accommodate is limited.

 Physical Topology in the Cisco Packet Tracer

Figure 10.7 The appearance of rack cabinets with devices

We begin to create a physical topology. It provides for two cities – city A and city B. One city is always created by default, its name should be changed to "City A". To do this, click on its old name, and then type a new one. If this is successful, enable options Options  Preferences  Interface  Show Device Name Labels (Ctrl+R) in PT. Then, add another city to the workspace. To add a site, use the buttons at the top of the workspace.

Figure 10.8 Buttons for adding city, buildings

The New City button adds a new city, new Building a new building, and New Closet adds a new station with equipment. In this case, click New City, and then the new city should appear in the workspace. By default, new objects appear in the upper-left corner of the area, so drag them to a different location so that cities don't obscure each other. Then, as in the case of the first city, change its name.

Figure 10.9 Two Cities in the Cisco Packet Tracer

Next, you need to create all the buildings you need. To do this, the location City A should be opened. A total of four buildings will be located in this city. Since the first, one default building is already in this city, you should add only three buildings (Building 2, 3, 4) in a manner analogous to adding cities using the New Building button, and then rename them to:

Building 1 , Building 2 , Building 3 , Building 4 .

 Physical Topology in the Cisco Packet Tracer

Figure 10.10 Created buildings

The next step is to create equipment stations in the buildings. Positions with equipment are created in the same way as cities or buildings. Enter the building where the appropriate cabinets are to be created (installed) (using the New Closet button).

Figure 10.11 For example, arranged desks and rack cabinets All cities, buildings, and positions (except for one named Intercity , which includes all newly added devices by default) can be removed by clicking the cross symbol in the toolbar and then on the object that needs to be removed. After creating the stations in the same way in other buildings, you can proceed to the next stage, i.e. placing devices in the topology.

10.1 Arranging Devices

To move a device to a location, you must first open its current location by any means. Then click the Move Object button, click on the device you want to move, and select its new location from the list. The device will be moved. In the same way, you can also move positions, buildings, and cities (but keep in mind that you can't move a larger object to a smaller object, such as a city to a building).

Figure 10.12 Changing the position of the device

10.2 Physical Cable Lengths and Distances In physical topologies, the actual distance between devices is taken into account (measured as the length of the physical cable in meters or feet). The unit of measurement of length is set using the Options  Preferences  Interface  Use Metric System . The length of the cable can be checked by guiding the mouse cursor over the cable. The actual distance between the devices determines whether communication will be possible. For connection by UTP or STP copper wire, the maximum distance is 100 m, with a longer connection, the devices will not be able to communicate. If devices more than 100 m apart are combined with each other, a device must be placed between them to amplify the signal, e.g. a repeater, which will amplify the signal, or, as in the case of our topology, use optical fibres.

 Physical Topology in the Cisco Packet Tracer

Figure 10.13 Checking the length of the cable

Distance is also important in wireless networks. The range of the wireless network is marked with a circle as in the picture below. Only devices inside the circle are within the network coverage.

To make it easier to orient yourself in distances, you can enable the coordinate grid. To do this, click on the Grid button in the bar above the workspace. In the window that appears, you can select the appropriate grids to decide in which areas ( Intercity, City, Building ) the grid should be turned on, as well as the distances to be measured (in meters). Grid-X refers to the horizontal axis, while Grid-Y refers to the vertical axis. You can also choose the colour of the drawn grid.

 Physical Topology in the Cisco Packet Tracer

Figure 10.14 Grid tab

This example enables a grid in cities that measures 200 meters horizontally and 100 meters vertically.

Figure 10.15 Distance grid and cities

10.3 Cable Management

The program allows us in physical topologies to have more control over the course of wiring. The first thing we can do is to create bend points ( Bend Points ), which are the points through which a given cable will pass.

Figure 10.16 Create a point

To create such a point, click the left mouse button on the cable, and then select Create Bend Point. The point you create is in the form of a red dot. Then we can freely drag the created point to get the desired effect. However, it should be remembered that the way the cable is routed affects its length.

Figure 10.17 Cable guided using BendPoint

Another function present in the program is the grouping of cables. Several grouped cables are routed together as if they were a single cable. To group several cables, you must first create Bend Points on them in the places where you want to group them. Then you just need to drag the point of one cable to the point of another. In this way, we will create Group Point , which is a point that groups cables. The red dot will change to a yellow square.

 Physical Topology in the Cisco Packet Tracer

Figure 10.18 Created Group Point

In order for several cables to be routed as a single cable, they must be grouped at least two points.

Figure 10.19 Several cables routed as a single

In addition, you can change the colour of the cables. To do this, click on the cable with the left mouse button, and then select the Color Cable option. In the window that appears, select the colour of the cable.

 Physical Topology in the Cisco Packet Tracer

Figure 10.20 Cable colouring panel

The acres of available colours is very similar to the colours used in MS-Paint. You can change the colour of all individual cables, but you cannot change the colour of cable groups.

Figure 10.21 Coloured cables

11 Skill Exercises – Part II

This chapter contains checking exercises for beginners users, testing their skills.

11.1 Configure Devices Using the Graphical Interface

11.1.1 Interface configuration, static routing

Create the topology shown in the figure below, and then use the graphical interface to configure the routers so that NETWORK 1 can communicate with NETWORK 2 . Use static routing.

Figure 11.1 Exercise’s topology

Solution:

 Create a topology as in the picture, connect the devices to each other using appropriate cables - if the device does not have the appropriate module, add it.

 Address and enable interfaces as in the diagram (Config tab → [appropriate interface]).

 PING connectivity to the two default gateways within NETWORK 1 and then within NETWORK 2 .

 Configure static routing in both directions (Config tab → Static).

 Use the tracert command to verify that NETWORK 1 can communicate with NETWORK 2.

11.1.2 Switch Modes, VLANs Configuration

Start by creating a topology as in the figure below. Address the end devices in the right way and create a database of three VLANs on both VLAN10, VLAN20 and VLAN30 switches. Assign these VLANs in such a way that only devices from a given VLAN can communicate with each other.

Figure 11.2 Exercise’s topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address the end devices so that they are on the main network (192.168.0.0/28).

 Create a VLAN database on both switches so that the names and numbers match (VLAN10, VLAN20 and VLAN30).

 On the Class 1 switch on the appropriate ports, change the operating modes and assign the appropriate VLANs.

 Repeat the same action on the Class 2 switch.

 Using the PING command, test communications within one VLAN, e.g. from Stand 1 to Laptop Stand 1 , and then test communication from VLAN10 to VLAN20 (it should fail).

11.2 Routing Protocols, Remote Management

11.2.1 RIPv2 and Configuration Using Telnet, Local Name Definition Create a topology consisting of four routers and several end devices and two switches, as shown below. Use fiber optic connections between routers Split, Makarska, Dubrovnik . Then address the devices according to the topology scheme. Each router is to be distinguished by other routers by its name (local definition of names). Also configure the dynamic routing protocol – RIP v2, so that Zagreb can exchange information with Dubrovnik , in which Laptop Admin is to have access to the configuration of each router using the Telnet protocol (password is the name of the router, e.g. " dubrovnik " for the Dubrovnik router).

Figure 11.3 Exercise topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address and enable the interfaces of network devices and end devices according to the scheme.

 Configure local name definitions on routers.

 Configure the Dynamic Routing Protocol - RIPv2 on each router, and then test the connection between Server and Computer Workstation .

 Set the configuration of the routers so that they can be accessed remotely using the Telnet protocol and then check if there is access from Laptop Admin to Zagreb .

11.2.2 RIPv2 and Configuration Using Telnet, Local Name Definition In the figure below, there is a topology that must be created and configured in such a way that the OSPF dynamic routing protocol ( AS 10 ) operates on the network, and each router in addition to its own ID in OSPF is to be accessible via a virtual Telnet terminal. On the SERVER HTTP device, create a web page that displays your name in green, you want every user of the network to have access to this page.

Figure 11.4 Exercise topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address and enable the interfaces of network devices and endpoints according to the topology scheme.

 Configure the OSPF dynamic routing protocol with an AS number of 10 and a area of 0 . Each router is to have a unique defined identifier.

 Set the routers so that they can be configured remotely using telnet and then try to access Router 2 from PC3 .

 Configure index.html on the HTTP Server device as intended.

 Try to access the website with the address 200.10.0.2 from PC1 .

 Test the connectivity between PC3 and PC2 with the tracert command.

11.2.3 EIGRP and Configuration via SSH, HTTP and DNS The required topology is shown in the figure below. Address it correctly and enable network interfaces according to the schema and configure the Dynamic Routing Protocol (EIGRP) ( AS 5 ). Also configure the routers in such a way that they can be accessed using the SSH protocol. An IP domain is eigrp.com . The SSH protocol is to be available on two channels: 0 and 1. When you have completed these steps, edit the HTML page on the HTTP Server so that the page displays any inscription in the middle. This page is to be available at www.anyname.com .

Figure 11.5 Exercise topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address and enable the interfaces of network devices and endpoints according to the topology scheme.

 Configure the EIGRP dynamic routing protocol with an AS number of 5.

 Position the routers so that they can be configured remotely using the SSH protocol. Create an admin account with admin password, use modulus 1024 and eigrp.com domain. Set the privileged mode password to enable .

 Configure index.html on the HTTP Server as intended.

 Add an entry on the DNS server so that the HTTP Server is available under the www.anyname.com.

 Test the connection by using the PING command between Personal Computer and Server DNS .

 Try displaying the www.anyname.com from Personal Computer page.

11.3 VLANs, Router on a Stick, Remote Management

11.3.1 Switch Modes, VLAN Configuration

Create a topology that consists of three offices connected to each other by three switches. You have to configure the switches in the right way so that the end devices can only communicate within their offices.

Figure 11.6 Exercise topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address endpoint interfaces according to the topology scheme.

 Configure the switches correctly, configure the VLAN database: three VLANs on each switch vlan10 - OFFICE1 , vlan20 - OFFICE2 , vlan30 - OFFICE3 .

 Change the modes of operation of the ports on the switches accordingly so that they match the assumptions.

 Check if you can communicate between offices – the result should be negative.

11.3.2 VLAN Configuration, Routing Between VLANs

In a logical topology, there should be four switches and one router in this exercise. Create a VLAN database that will include: VLAN11 , VLAN22 and VLAN33 . According to the topology scheme, assign VLANs to ports and configure the router in such a way that VLANs can communicate with each other. There is an additional emergency connection between Switch 1 and Switch 2 .

Figure 11.7 Exercise topology

Solution:

 Create a logical topology as in the figure, connect the devices to each other using the appropriate cables.

 Address endpoint interfaces according to the schema.

 Go to the switches and configure the VLAN database - three VLANs on each switch: 11 - VLAN11, 22 - VLAN22 , 33 - VLAN33 .

 Change the modes of operation of the ports on the switches accordingly so that they match the assumptions.

 Check if you can communicate between VLANs – the result should be negative.

 Configure the router interface and sub-interfaces to route traffic between VLANs.

 Try to send an ICMP packet between VLAN11 and VLAN33.

 The result should be positive . 

11.3.3 Remote Switch Management

Build a simple topology that includes one wireless router, two switches, and one Admin mobile device. Configure the switches so that the S1 is configurable remotely using Telnet. The password is zaq1 , the login account is admin , and the privileged mode password is @WSX.

In turn, the S2 switch is to be remotely accessible using the SSHv2 protocol – logging in is to be performed only to the admin user account with the admin password, while access to the privileged mode is to be protected by a qwerty password. An IP domain is a switch.com .

Figure 11.8 Exercise’s topology

Solution:

 Create a topology according to the drawing, connect the devices to each other using the appropriate cables.

 Address the interfaces of network devices according to the topology drawing.

 Make sure that the Admin computer gets a dynamic IP address.

 Configure S1 so that network access can be possible using a virtual terminal and Telnet . Use the admin user, the password for privileged mode @WSX , and the password for the zaq1 terminal.

 Configure S2 so that network access can be possible using a virtual terminal and the SSHv2 protocol. Use the admin user, the privileged mode password qwerty , and the IP domain switch.com .

 Perform an access check using Telnet from the Admin smartphone to S1 and using SSH to S2 .

11.3.4 Protocol REP in Switches

Perform REP configuration in the following point-to-point topology.

Figure 11.9 REP Segment Topology

Solution:

 Create a topology according to the figure shown.

 Configure addressing of SALEM, PORTLAND, SAN FRANCISCO, DENVER, LINCOLN, ATLANTA, computers in the local network (next addresses: 10.0.0.1/8, 10.0.0.2/8, 10.0.0.3/8, 10.0.0.4/8, 10.0.0.5/8,

10.0.0.6/8)

 Make connections of SALEM, PORTLAND, SAN FRANCISCO, DENVER, LINCOLN, ATLANTA computers with appropriate switches: OREGON, MAINE, CALIFORNIA, COLORADO, NEBRASKA, GEORGIA, using Fast Ethernet 1/1 interfaces.

 Connect the switches to each other using patch cables in TRUNK mode:

 Fa1/2 LINCOLN - Fa1/2 ATLANTA

 Gi1/1 OREGON - Gi1/1 MAINE

 Gi1/2 MAINE - Gi1/2 NEBRASKA

 Gi1/1 NEBRASKA - Gi1/1 COLORADO

 Gi1/2 COLORADO - Gi1/2 CALIFORNIA

 Configure the REP segment number 1 in each switch using the commands:

interface <interface name>

switchport mode trunk

rep segment 1

12 Working with Large Topologies

This chapter describes the use of clouds and the basics of Multiuser mode and is intended for intermediate users.

12.1 Introduction to Device Grouping

What is the use of device grouping? Very often, the person responsible for the design of the network, before implementing it into practical operation, creates a network model using simulation programs.

When creating complex networks that contain multiple subnets, each with a different purpose and a different area of operation, network design becomes increasingly complex. Therefore, it becomes very useful for the network designer to be able to divide the network into subnets also in a graphical form.

The main purpose of grouping devices when creating more complex networks is the need to group them so that the final logical scheme of the network with a high degree of complexity contains fewer graphic elements depicted on the screen. Device grouping (according to the original Cisco Systems Clustering devices nomenclature) does not affect the logical configuration of the network (addressing) and its functioning. The original English name in the Cisco Packet Tracer for grouped devices (as originally named by Cisco Systems) is Cluster . The book uses the name Cloud, because according to the subjective opinion of the authors, this Polish equivalent most closely matches the icon representing a group of devices.

The Cisco Packet Tracer also allows you to move individual devices or their groups between clouds and create a hierarchical structure of clouds (sub cloud in the clouds).

12.2 Device Grouping – Description of Tool Buttons At the top of the Cisco Packet Tracer is the main menu and the toolbar. On the left (under the toolbar) is a switch between the logical and physical modes of the network. In order to perform the basic operations describ e d in th is s ub s e c tio n, we w ill set this switch to Logical mode.

Figure 12.1 Logical topology area

In the Logical view, the blue bar contains the following buttons: [ Root ], Go back one level, New Cluster, Move Object, Set Tiled Background, Environment. To perform actions related to clouds, we will use the following buttons.

Figure 12.2 Buttons in logical topology view

After starting the program in the logical topology view, all devices are placed at the main level ([Root] ). To familiarize yourself with the program's capabilities regarding the grouping of devices in the clouds, we will follow the steps described in the next subsection.

12.3 Device Grouping – Step ‐ By ‐ Step Algorithm We start by creating a simple network, consisting of a router, a switch and five computers.

Figure 12.3 Example topology

To group devices into one graphic object, select a group of devices (using the Select tool).

Figure 12.4 Selecting tool, located at the top left

 Working with Large Topologies

Figure 12.5 Devices selected with the Select tool

After selecting the device group, click the New Cluster button.

Figure 12.6 Create a new cloud

We have created a new graphic object. In the area of logical topology, a cloud called Cluster0 appeared. We did a simple grouping of devices in the cloud.

Figure 12.7 A new cloud called Cluster0

To enter the cloud, we click on the cloud with the left mouse button.

Figure 12.8 Cluster0 cloud content view

To exit the cloud, use the Back button. In this way, the main logical topology level is returned.

Figure 12.9 Exiting the Cluster0 cloud

12.4 Move a Single Device From the Cloud to the Root Level In the example below, we will continue cloud operations, that is, we will move the router from the Cluster0 cloud to the main topology level. To move the router out of the cloud, click Move Object , and then select the router.

 Working with Large Topologies

Figure 12.10 Select a Cluster0 cloud router

To move the router to the Root level, we select the Move to Root option. The router will be removed from the cloud, while the cable connection will remain, as shown in the figure below. After exiting the cloud, the router will appear at the main level.

Figure 12.11 Cluster0 Cloud Topology

At the main level, a router will appear and as you can see in the figure, the router is located outside the Cluster0 cloud.

 Working with Large Topologies

Figure 12.12 Root level topology

12.5 Move a Single Device from the Root Level to the Cloud In the following example, we will move the router from the main topology to the Cluster0 cloud. To move the router from the Root level to the cloud called Cluster0 , we must first click the Move Object button, and then select the router.

Figure 12.13 Root level topology before moving the router

After performing this option, we will notice that the router will disappear from the main level, but will appear at the Cluster0 cloud level. To check this, we need to go to the Cluster0 cloud.

To go to the cloud we click on it. The contents of the Cluster0 cloud will appear, where you can see that the router is still properly connected to the other devices. The Cluster0 cloud topology is shown in the figure.

 Working with Large Topologies

Figure 12.14 Cloud-level topology after router transfer

12.6 Purpose of the Set Tiled Background Button In the Cisco Packet Tracer, you can change the icons that represent devices and configure the topology background. The example shown in this section is provided for informational purposes only.

To take advantage of this capability, you must first create icon files that represent devices and backgrounds. They should be created using any external program that can save images in PNG or JPG format. The recommended resolution for an icon file is: 45 pixels x 31 pixels . Note: Higher resolutions will be automatically scaled to lower resolutions . Use the Set Tiled Background button on the blue bar to configure the background image for the current logical topology. To change the default background of the logical topology, click the Set Tiled Background button.

Figure 12.15 Set Tiled Background button

At the bottom of the window, set the Display Tiled Background Image option. Then we select the background image file using the Browse button.

 Working with Large Topologies

Figure 12.16 Select a file for the background and set background display options An example of how the logical topology looks like as bellow showed, when you change the default values of Background Image.

Figure 12.17 Topology after background change

The second example of the logical topology in the Cluster0 cloud after changing the default values of Background Image and Cluster Icon.

Figure 12.18 Cluster icon after changing the icon

Figure 12.19 Example Topology after background change for Cluster0

12.7 Rename a Cloud

Changing the name of the cloud can be freely carried out provided that the names of the clouds differ from each other. This operation is very simple, because you only need to click on the name under the cloud symbol and edit the appropriate text. Remember, however, that it is a good habit to use cloud names according to their purpose or area of application, e.g. "Internet", "ISP", "Cellular network", "ALABAMA". It is not recommended to leave the default generated names of type "Cluster0", because in the case of more complex networks, they will not inform us about the nature of a given subnet.

12.8 Multiuser Mode

Multiuser, i.e. communication with many users, allows you to create point-to-point (peer) connections between many Cisco Packet Tracer instances. What is an instance? An instance is the launch of a given application (in this case the Cisco Packet Tracer) as a separate process in an operating system, e.g. Windows.

By enabling communication between the Cisco Packet Tracer instances, the door opens to new types of tasks and variety of work in groups. Communication between different Packet Tracer stations is via TCP and uses port 38000 by default. The default password is cisco.

To start working in two different instances, first run the Cisco Packet Tracer in two windows and execute the two basic networks. In the first one there will be a computer and a router, and in the second one there will be a router and a laptop. The devices are addressed as shown in the diagram below.

Figure 12.20 Topology to configure Mutliuser - instance 1

Figure 12.21 Topology to configure multiuser - instance 2

After configuring two networks in two separate instances, select the Extensions →Multiuser →Port Visibility tab in the tabs at the top of the program to set which ports are visible in the second instance of the program. On both instances, select one port of the Router.

 Working with Large Topologies

Figure 12.22 Multiuser configuration options

Figure 12.23 Enable port visibility in another instance

Once you know which ports will be visible in another instance, set a default password ( cisco ) for connections and change the listening so that all connections are activated as shown in the figure below.

 Working with Large Topologies

Figure 12.24 Change your password and listening options

This should be done in the same way in the case of the second instance. Now you need to add a new device to one of our instances (no matter which one you choose - in our example it is Instance 1 ). This device is called Remote Network and is named as Multiuser .

Figure 12.25 Remote Network device

Figure 12.26 Appearance of the topology when you add a new device According to which port we have chosen before, in order to be visible, you should pull the connection to Peer1 and choose to create a new connection.

Figure 12.27 Connection to Peer1

We are left with the configuration of the Peer1 cloud so that it connects to the second instance, which is enabled at all times. Select the Outgoing connection type and enter the appropriate password that you have previously set.

Figure 12.28 Connection to the second instance

If everything is well configured, then after clicking the Connect button, a new device with a yellowish colour should appear in Instance 2 (number two).  Working with Large Topologies

Figure 12.29 New cloud Peer2 in Instance 2

We select the patch cable and from the appropriate interface Router - Instance 2 we connect to the router, which is located in another instance.

Figure 12.30 Connect to a router in another instance

To test our connection, we will address the interfaces between the routers so that they are in the 10.10.0.0/30 network and on each router we will configure the simplest dynamic routing protocol – RIPv2 .

Figure 12.31 Instance 1 - ready example

 Working with Large Topologies

Figure 12.32 Instance 2 - ready example

After conducting a simple PING command from PC to Laptop, we get a positive result, which proves that our network between instances works in the correct way.

Figure 12.33 Successful PING from PC to Laptop

This is just a simple example to show you how to configure the simplest connection between instances. Of course, the possibilities are endless and you can use this function in a very interesting way, so we encourage you to experiment.

13 DHCP Protocol for IPV4

This chapter describes DHCP for IPv4.

13.1 Introduction to DHCP

13.1.1 DHCP Basics

The DHCP service is very widely used in large networks that we encounter every day. This chapter describes this topic in more detail compared to what has already been written in the previous sections. For the record and consolidation, we'll discuss what DHCP is all about from the beginning:

Unlike static IP configuration of network devices, Dynamic Host Configuration Protocol (DHCP) provides dynamic configuration for network devices (hosts). Network device after receiving the following information:

 IP address

 Netmask

 Default gateway

 and optional DNS server address

can communicate with other devices. Dynamic host configuration requires that there be at least one properly functioning DHCP server on the network.

A DHCP server can be a computer with a network operating system installed (e.g., Linux, Windows Server, or another) or any router running a DHCP service (e.g., a Cisco or other router, MikroTik, a wireless ISR router). The most important configuration information obtained from the DHCP server is:

 Assigned host IP address,

 Assigned host subnet mask,

 Assigned default gateway address,

 DNS server address

 Lease time, i.e. the time for which a given configuration applies to us The principle of the DHCP service (the dynamic process of obtaining configuration data from a DHCP server) consists of four phases, shown in the following figure.

Figure 13.1 How the DHCP service (process) works

13.1.2 DHCP Phases

Phase 1: Searching for a DHCP server

The client ( PC ) sends a DHCPDISCOVER message to the entire network to get feedback on whether a DHCP server exists on the network. In general, there can be three situations:

 there is no DHCP server on the network, or the network is corrupted and the client does not have access to the DHCP server,

 There are multiple DHCP servers on the network,

 there is only one DHCP server on the network.

Let's answer the following question: What happens if a client does not have access to DHCP? If for any reason the client cannot receive a response from the DHCP server, by default it receives a random IP address from the 169.254.0.0/16 subnet. In this case, the customer will receive an address from the range of:

The above address range is intentionally designed to avoid accidental conflicts with other host addresses on the network. This range is officially recognized as a reserved pool of part of the Class B addresses, only for DHCP failure to obtain dynamic IP (see RFC 3927 ). Examples illustrating this situation can be found in the figures below.

Figure 13.2 The network is working properly and there is no DHCP server configured

Figure 13.3 The network is corrupted and there is no access to the DHCP server Let's answer the next question: What happens when we have multiple DHCP servers on our network?

If we have multiple DHCP servers in the network offering IP address configuration, the client will choose the offer that will be the first to be received from any DHCP server (i.e. the client will choose the DHCP server that first reported). The remaining servers will not be supported. Below we see a situation in which there are two running DHCP servers on the network (for example, one of them offers configuration on the 192.168.0./24 subnet, and the other on the 10.0.0.0/8 subnet).

Figure 13.4 The network is working properly and contains two DHCP servers In the presented example, a PC can get the following configuration:

Figure 13.5 PC configuration obtained with Router

or configuration:

Figure 13.6 PC Configuration obtained from DHCP Server Next, let's answer the next question.

What happens if we have one DHCP server on the network? If we have only one DHCP server in the network, this is the simplest situation, because the offered configuration of IP addresses will always be sent from only one server. After completing Phase 1, the DHCP server found responds to the client with a message containing an addressing offer (the server moves to perform Phase 2). Phase 2: Send a DHCP server proposal to all DHCP clients The DHCP server sends a DHCPOFFER message to all DHCP clients (DHCP hosts) containing the proposed address parameters. The main transmitted parameters are contained in the DHCPOFFER message fields:

 YIADDR (ang. your IP address ) – the proposed IP address of the host,

 Subnet Mask – subnet mask,

 Source Address – source address (IP address of the DHCP server),

 Destination Address – broadcast destination address (255.255.255.255), In this way, clients receive information about which server reported first ( Source Address ) and which address it offers to the client ( YIADDR ).

Figure 13.7 Send a DHCPOFFER response from the DHCP Server Phase 3: Send a request for approval of a proposal to the DHCP server The DHCP server waits for DHCPREQUEST messages from clients. The rule applies "the customer who confirmed the offer first is the first ". For example, PC 1 . PC 1 sends a DHCPREQUEST message to the DHCP server requesting that the offered address configuration be assigned.

Figure 13.8 Send a DHCPREQUEST request to the DHCP server Phase 4: DHCP server approval of the addressing proposal After completing Phase 3, the DHCP server sends a DHCPACK message confirming the DHCP client's request and assigns address parameters (and their validity time, i.e. lease time ). The default lease time varies and depends on the operating system that offers DHCP. The process of dynamically configuring client addressing is completed.

Figure 13.9 Send DHCPACK confirmation to DHCP client - Configuration completes

PC 1 has been assigned an address configuration and is therefore ready to communicate with the network.

13.2 Configuring DHCP on the Server

Before configuring the DHCP server service, we will configure its server network adapter, i.e. we will assign the following address data to it:

 IP address of the server,

 subnet mask,

 default gateway (optional)

As it has often been reworked, we will let go of showing how to do it and go straight to the configuration of the service.

13.2.1 Configuring the DHCP Server Service

Setting up DHCP on the server is very easy. To do this, activate the DHCP service and enter the appropriate values into the following fields in the Services  DHCP :

 Pool Name – name of the IP address pool,

 Default Gateway – default gateway address,

 DNS Server – the address of the default DNS server,

 Start IP Address – the initial (first) address in the IP address pool,

 Subnet Mask – subnet mask,

 Maximum number of Users – the maximum number of IP addresses in the pool. To configure DHCP on the server, follow these steps:

Step 1. We choose a service

Select DHCP Server , go to the Services tab, and then select the DHCP service. Step 2. We activate the DHCP service

Select the On option for DHCP.

Figure 13.10 Activate DHCP on the server

Step 3. Configure DHCP service parameters

We fill in the appropriate fields for the service:

 Pool Name – name of the IP address pool,

 Default Gateway – default gateway address,

 DNS Server – the address of the default DNS server,

 Start IP Address – the initial (first) address in the IP address pool,

 Subnet Mask – subnet mask,

 Maximum number of Users – the maximum number of IP addresses in the pool,

Figure 13.11 Configure DHCP parameters on the server

Step 4. We approve DHCP parameters

To confirm and save DHCP parameters, click save .

 DHCP Protocol for IPV4

Figure 13.12 Saving DHCP parameters to the server

Step 5. We check the operation of the DHCP service

PC1, PC2, PC3 received IPv4 configuration from Server1. We can check this without using the command line or configuration windows. To check the current configuration of IP addresses for a given device, we move the mouse pointer to the appropriate computer icon. A small information frame in grey will be displayed, which will show us the configuration data of a given computer: the current IP address, subnet prefix, DNS server address.

Figure 13.13 Check IPv4 addresses on PC1

We can also check whether the computers are communicating with the server. We use the single envelope symbol and ping from PC 1 and PC 2 to the DHCP Server.

Figure 13.14 Check the communication of computers with the server

13.2.2 Erasing DHCP on the Server

The term "Erasing DHCP on the server" is understood to mean disabling the DHCP service or deleting the address pool in the DHCP service.

13.2.3 Disabling DHCP on the Server

Select a DHCP server. In the Services  DHCP tab, select the Off option.

Figure 13.15 DHCP server is disabled

13.2.4 Deleting DHCP Address Pool on the Server

You can only remove an address pool from the DHCP server service if you have more than one pool. When we have only one pool defined, it must remain (it cannot be deleted). Suppose you have two address pools defined:

 serverPool (5 addresses in subnet 10.0.0.0/24) – pool one, default,

 secondPool (50 addresses on the 192.168.1.0/24 subnet) – second pool.

Figure 13.16 Defined DHCP address pools

To delete the pool called secondPool , go to the Services  DHCP tab, select the secondPool pool, and then click the Remove button.

Figure 13.17 Delete a DHCP address pool

Figure 13.18 DHCP address pool has been removed

13.3 Configuring DHCP on Your Router

In this example, we will configure the DHCP service as intended in the following table.

Table 13.1 DHCP configuration data

We will use the above configuration data for the topology shown in the figure.

Figure 13.19 Network topology with DHCP server router and DHCP clients Before configuring the DHCP service on the router, we need to make sure that the configurations of the router interfaces have been performed correctly. The interface should have the address 192.168.0.1 with a subnet mask /24.

If the configurations of the router interfaces are correct, then we proceed to the configuration of the DHCP server router.

Configuration of the Router (DHCP server) will be performed in the following stages:

 configuring the Fa0/0 interface (default gateway) of the DHCP server,

 configure the address pool on the router,

 displaying an array of assigned addresses,

 checking the operation of the service and the communication of computers with the router.

Configuring the Router Interface (DHCP Server)

We perform the configuration of the default gateway (Fa0/0 interface) of the Router router using the CLI command line.

We go to the global configuration mode and address the interface in the appropriate way and enable it.

Figure 13.20 Configure the Router's Fa0/0 interface as the default gateway

13.3.1 Configure the Router (DHCP Server) Address Pool

After configuring the default gateway, we proceed to the proper configuration of the DHCP service on the router.

Practical note: after each change of DHCP configuration, we must renew the addressing lease on computers (DHCP clients) using the ipconfig /renew command.

Figure 13.21 Renew your addressing lease on PC1

Our first task will be to inform the router that its own address cannot be assigned to computers (DHCP clients).

If we do not do this, there may be an address conflict on the network (so-called duplicate IP addresses may occur on the network).

To do this, use the ip dhcp excluded-address command in the router's global configuration mode to indicate to the router a range of addresses that will not be allocated to DHCP clients.

In our case, the command will have the following form:

Figure 13.22 Router line with a command to exclude one address from the DHCP pool

Now we move from the global configuration mode to the address pool configuration mode on the DHCP router-server. The command used for this is  ip dhcp pool <name>

Figure 13.23 Router line after entering DHCP pool configuration mode Now we can configure the DHCP pool (according to the data at the beginning of this subsection). For this purpose, we will use the following commands, described below: default-router <IP address> - specify the default gateway dns-server <IP address> - DNS server determination network <IP address> <netmask> - the network from which addresses will be assigned

Figure 13.24 Router line with commands to configure the DHCP pool. We use the show running–config command to check the DHCP configuration.

Figure 13.25 A portion of the configuration of the current router with DHCP configuration commands.

13.3.2 Viewing the Assigned IP Address Array in DHCP

To display the array of assigned IP addresses on the router (DHCP server), we execute, in privileged mode, the command show ip dhcp binding .

Figure 13.26 An array of assigned IP addresses by DHCP.

The following displayed columns contain the following information:

 IP address - assigned IPv4 address to the end device,

 Client ID/Hardware address - MAC address of the device's network card,

 Lease expiration - IP address lease validity (unspecified here – the Cisco Packet Tracer does not support this option),

 Type - how to assign an IPv4 address to the end device.

13.3.3 Verifying the DHCP Service Is Working on the Router After completing the configuration of the router, we check whether the computers have received the correct addressing. The best and surest way is to renew the IP lease on all computers using the  ipconfig /renew .

Figure 13.27 Renewed addressing lease on PC1 and PC2.

Next, we can check the communication of computers with the router. To do this, we will use the ping command or the symbol of a single envelope. As you can see in the figure, the ping response is correct.

Figure 13.28 Example of checking communication between PC 1 and a router with the address 10.0.0.1

We can also check the communication between computers, for example, between PC 1 and PC 2 .

Figure 13.29 Example of checking communication between PC1 and PC2

13.3.4 Deleting the DHCP Configuration on the Router (DHCP Server) In order to remove the current DHCP configuration on the server (Server2 router), we will use the previously learned commands and the keyword no, adding it at the beginning of the configuration commands:

Figure 13.30 Commands that remove the current DHCP configuration from the Server2 router.

13.3.5 Deleting DHCP Configurations on Computers (DHCP Clients) To remove the current DHCP configuration on clients (PC1, PC2), we will use the ipconfig command with the /release option. The command must be executed on all computers.

Figure 13.31 Command to remove the current DHCP configuration from PC 1

13.4 DHCP on a Network with Multiple Routers When dealing with networks composed of many routers, it becomes a bit more difficult to configure DHCP. By default, each router divides the network into separate broadcast domains and therefore they cannot forward DHCP messages between routers. However, this is possible provided that we configure the so-called intermediary routers to forward DHCP requests ( broadcast messages ) to the correct DHCP server. We will apply the topology shown in the figure below.

Figure 13.32 Network topology with multiple intermediary routers We assume that the routers have been configured correctly - they have been addressed as in the diagram and the RIPv2 routing protocol between connections has been configured. In this example, we will configure DHCP on a network consisting of multiple intermediary routers and a router acting as a DHCP server, as intended in the following table.

Table 13.2 DHCP Configuration Parameters

Configuration of a network consisting of multiple intermediary routers and a router that acts as a DHCP server will be performed in three steps.

13.4.1 Set Up an Intermediary Router

To configure an intermediary router, we select the nearest router connected to the subnet of computers. In this example, the intermediary router closest to the subnet of PC1, PC2, and Laptop is Router1.

To configure it for the role of message forwarding to the DHCP service running on router Router3, we need to execute the command

ip helper-address <adres serwera DHCP>

and we perform them on the interface to which queries for a dynamic IP address come.

Figure 13.33 Router1 router line with commands to configure DHCP server address

Router1 can now forward DHCP messages from computers to routers with the address

200.0.0.6. Similarly, Router2 should be configured.

13.4.2 Start DHCP and Configure the Address Pool

In order to start and configure the address pool DHCP_Server of the router Router3 , we need to set the following parameters

Figure 13.34 Router3 router line with DHCP Server configuration commands After configuring the address pool of the R3 main router, we can check what addresses have been assigned to the computers. Computers PC1... PC4 obtained IPv4 addresses using the automatic DHCP service.

Figure 13.35 Obtained IP address on Laptop

13.4.3 Check the Array of Assigned IP Addresses on the Router To display the array of assigned IP addresses on the router ( DHCP server ), we use (in privileged mode) on the router the command

show ip dhcp binding

Figure 13.36 Current router table with DHCP address quotas

13.5 Configuring DHCP on the Wireless Router

13.5.1 Configuring DHCP on the WRT300N

In this example, we will configure DHCP on the ISRWRT300N wireless router, as intended in the following table.

Table 13.3 Configuring Wireless DHCP on the WRT300N

We will use the above configuration data for the topology shown in the figure.  DHCP Protocol for IPV4

Figure 13.37 Network topology with WRT300N router and wireless clients In the local wireless network we will place three devices equipped with Wi-Fi network adapters (DHCP clients): PC, Laptop and Smartphone , and the WRT300N wireless router acting as a DHCP server and default gateway. In addition, we will connect the Internet interface of the WRT300N router, with an external cable network consisting of a switch: Switch0 , router R1 and DNS server with the address 10.0.0.6. If you want to configure DHCP so that endpoints are randomly assigned IP addresses from a specific address pool on the 192.168.0.0/24 subnet, follow these steps: Step 1. Connect Laptop (ADMIN) to WRT300N

We connect the Laptop (ADMIN) to Ethernet port 1 of the WRT300N router, using an Ethernet cable (simple).

Figure 13.38 Connecting Laptop (ADMIN) to WRT300N to configure the router Step 2. Configure Laptop (ADMIN)

We configure a static IP address and subnet mask for the Ethernet Laptop(ADMIN) network adapter (any address except 192.168.0.1, since it is the default configuration address of the WRT300N router). Configuration can be done using the IP Configuration applet in the Desktop tab.

Figure 13.39 Configuring the Static IP Address of the Laptop(ADMIN) Device Step 3. Launch a Web Browser on Laptop (ADMIN)

On laptop (ADMIN) we run a web browser. To do this, select the Laptop computer (ADMIN), the Desktop tab, and then the Web Browser applet.

 DHCP Protocol for IPV4

Figure 13.40 Applet Web Browser

Step 4. Enter the default configuration address of the WRT300N router In the Web Browser , in the URL field, enter the default configuration address of the router 192.168.0.1 and click the Go button.

Figure 13.41 Default configuration address for WRT300N

Step 5. Log into the WRT300N router

In the browser, the Authorization window will appear, in which we must enter the login and password for the router. By default, these are: admin, admin .

Figure 13.42 Authorizing access to the WRT300N router

Step 6. Enable DHCP Server service

The window of the WRT30N router configuration program will appear, in which we must go to the Setup menu and the Network Setup option.

Figure 13.43 Network Setup menu and Network Setup option We need to set the following fields: IP Address to 192.168.0.1 and Subnet Mask to

255.255.255.0. You must also select DHCP Server: Enabled .

Step 7. Configure the address pool in DHCP

In the Network Setup option there is a section called DHCP Server Settings that we need to configure. In this section, we set the following required DHCP parameters described in the assumptions:

 Start IP Address - the first available IP address (in our example 192.168.0.11)

 Maximum number - the maximum number of users dynamically getting IP addresses (in our example, four users)

 Static DNS 1 - DNS server address (in our example 10.0.0.6) Note: The field named IP Address Range contains a range of dynamically assigned IP addresses. It is automatically generated after the configuration is approved based on the values provided in the fields: Start IP Address, Maximum number .

 DHCP Protocol for IPV4

Figure 13.44 DHCP Server Settings section

Step 8. Save the configuration of the WRT300N router

Once the configuration of the DHCP address pool is complete, we must save it so that when the router is restarted, the configuration that we have just done is loaded. To save the configuration, go to the bottom of the screen of the current window and click the Save Settings button.

Figure 13.45 Button to save the current configuration of the WRT300N router We receive a message confirming that the settings have been saved and click on the "Continue" link.

Figure 13.46 A message confirming that the settings of the WRT300N router have been saved.

Step 9. Perform final activities

After saving the router configuration, we check whether the end devices are turned on, connected to the wireless network and whether they have received the appropriate IP addresses from the DHCP service.

Figure 13.47 Dynamically obtain the right IP address

13.5.2 Configuring DHCP Based on MAC Addresses

This example is a modification of the previous one (addressing and topology are the same). Now we will assign IP addresses based on the MAC addresses of the end devices. This technique is referred to as MAC Reservation . It works by assigning only a specific IP address to a specific physical MAC address.

To configure the DHCP service based on MAC addresses, we must first create a table of MAC addresses and corresponding IP addresses, which will facilitate our subsequent configuration. The subnet addressing in our example is listed in the following table.

Table 13.4 Assignment of MAC addresses to IP addresses for end devices. Step 1. Log into the WRT300N router from a Laptop (ADMIN)

 DHCP Protocol for IPV4

Figure 13.48 Logging in to the WRT300N

Step 2. Configure MAC address assignments

We perform DHCP configuration using IP addresses based on MAC addresses. The window of the WRT30N router configuration program will appear, in which we must go to the Setup menu and the Network Setup option. Click the DHCP Reservation button. A dialog box appears that contains the following sections:

 Select Clients from DHCP Tables - selection of clients from the DHCP table,

 Manually Adding Client - manual adding of DHCP client,

 Client Already Reserved - list of reserved DHCP clients

Figure 13.49 Manually Adding Client section

Now we add the names of the end devices, the IP addresses to be assigned and the MAC addresses, thanks to which the server will know to whom to assign which IP address. Step 3. Save the configuration of reserved MAC addresses

To save the added configurations of MAC address ranges to IP addresses, we need to go to the Clients Already Reserved section and click on the Save Settings button.

Figure 13.50 Saving settings in the Clients Already Reserved section Step 4.  Perform final activities

After saving the router configuration, check whether the end devices are turned on, disconnect the Laptop (ADMIN) device from the Wireless Router and proceed to check the DHCP server configuration with address reservation.

Step 5. Verify the operation of DHCP based on MAC addresses Having saved the configuration of the router, we can see that all wireless connections have been broken for a while and then compiled again, only this time the IP addresses that have been assigned to the end devices match their MAC addresses. We can test it on a PC device by checking what address the device has.

 DHCP Protocol for IPV4

Figure 13.51 Checking the IP address of a PC device

As we can see, the address matches the one that was reserved on the DHCP server for a given MAC address. Now, no other device will receive this IP address.

This chapter contains skill exercises for advanced users to test their skills.

14.1 Grouping Devices and Combine Two Instances of the Program

14.1.1 Grouping Devices

Create the topology shown in the figure below. Then, address the network and end devices appropriately and configure the EIGRP routing protocol (AS 50) so that the two networks can communicate with each other. Then, group devices so that Network 1 is one device group with the same name, and Network 2 is the second device group with the same name.

Figure 14.1 Exercise’s topology

Solution:

 Create a topology as in the picture, connect the devices to each other using the appropriate cables.

 Address network and end devices according to the scheme and enable interfaces.

 Configure the dynamic routing protocol - EIGRP (AS 50) on all routers taking into account each adjacent network.

 Create a DNS entry on the DNS Server for the address 200.0.0.10 available at www.http.com , and create an HTTP page on the HTTP Server on which it will display text "HTTP Page".

 Group devices from Network 1 into Area 1 and Network 2 into Area 2 .

 Test the connection using the PING command between two groups of devices and try to get the site www.http.com , from PC 2 . 

14.1.2 Device Grouping and Multiuser Function

Create a topology as in the figure below. You will need the Cisco Packet Tracer running twice - one time for each area. Once you've created the topology, address device interfaces appropriately and enable them. Configure the OSPF Dynamic Routing Protocol (AS 10) on the routers. Group your devices into two areas: Area 1 and Area 2 . Then connect the two instances together using the multiuser function using the multiuser password and the corresponding router interfaces.

Figure 14.2 Area Topology 1

Figure 14.3 Area Topology 2

Solution:

 Following the examples of the two figures above, create a topology in two separate Cisco Packet Tracer windows.

 Address and enable device interfaces appropriately.

 Configure the OSPF routing protocol (AS 10) on the routers. Use router-id to recognize each router.

 Group devices into two areas - Area 1 and Area 2 .

 Connect two grouped areas together using the multiuser function. Use the multiuser password and the interfaces shown in the diagram.

 Test the connection between PC and Server using any available tool.

14.2 DHCP for IPv4

14.2.1 Configuring DHCP on the Server

In the logical topology, this exercise will have four computer workstations, one switch, and one server that will act as a DHCP server. The addresses that the computer stations will receive will be in the range of 192.168.10.10-192.168.10.13 and users who can receive addresses are limited to four. The default gateway address is a fictitious router address: 192.168.10.254, while the DNS server address and TFTP server address are the address of our server.

Figure 14.4 Exercise’s topology

Solution:

 Create a topology as in the figure above.

 Address the DHCP Server device interface.

 Enable the DHCP service on the server.

 Configure DHCP to allocate four addresses in the range 192.168.10.10-

192.168.10.13. The default gateway is 192.168.10.254, the server address is the DNS server address, and the TFTP server address.

 On four computer stations, switch IP addressing to dynamic and check that the stations have received the correct addresses.

 If your positions have received the appropriate address, try using the PING command to communicate with the DHCP server . 

14.2.2 Configuring DHCP on the Router

Create a logical topology that consists of one router, one switch, and five end users. In this exercise, the router will serve us as a DHCP server with a pool called POOL and addresses

Figure 14.5 Exercise’s topology

Solution:

 Transfer the configuration from the figure above to your logical topology.

 Enter the router using the console on Laptop (ADMIN) and address the appropriate interface and enable it.

 Create a DHCP address pool called POOL with addresses from the 9.0.0.0/24 network, the default gateway that is this router, and the DNS server that is available at 9.0.0.254.

 Reserve addresses in the range 9.0.0.1-9.0.0.10.

 Switch to end devices and assign dynamic addressing to them.

 Test the connection between the hosts and between the end devices and the Router device using any tool.

14.2.3 Configuring DHCP on the Wireless Router

In the Cisco Packet Tracer, create a topology such as the one shown in the figure below. The wireless network settings remain the default. Configure the router's Ethernet address to 50.0.0.1/24. The DNS server obtains the address dynamically from the DHCP service on the Wireless Router, but it has a reservation of the address 50.0.0.254 to its MAC address. In turn, two wireless devices randomly get addresses from the 50.0.0.0/24 pool, which starts giving away addresses from the address 50.0.0.100. The maximum number of users is 10.

Figure 14.6 Exercise’s topology

Solution:

 Create a topology like the one shown in the figure above.

 Configure the Ethernet port on the Wireless Router to be assigned the address

50.0.0.1.

 Reserve the address 50.0.0.254 for the MAC address of the DNS Server device.

 Configure DHCP on the Wireless Router to distribute addresses from the

50.0.0.0/24 network starting at 50.0.0.100 and limited to a maximum of 10 end users.

 From a mobile device - Smartphone try to use the tracert 50.0.0.254 command to perform a connection test with the DNS Server .

14.2.4 DHCP Configuration on a Server That Is on a Remote Network The logical topology for this exercise is shown in the figure below. As we can see, we can distinguish four routers ( Up, Left, Right, Down ), a DHCP server at the very bottom and six end users, so-called Hosts . Address all devices as shown, and then configure the EIGRP Dynamic Routing Protocol (AS 66) between the routers. On the DHCP Server device, configure the DHCP service to have three separate pools, named PULA1, PULA2, and PULA3. Each concerns one network - e.g. PULA1 is a pool of addresses at the Left router. The default gateways are the corresponding router addresses, and the DNS and TFTP server addresses are the DHCP Server device address. Then indicate to the routers on the appropriate interfaces what IP address the device that acts as the DHCP server has.

Figure 14.7 Exercise’s topology

Solution:

 Create the logical topology shown in the figure above.

 Address and enable the device interfaces accordingly, as shown in the diagram.

 Configure the dynamic routing protocol - EIGRP (AS 66) between routers taking into account each adjacent network.

 On the DHCP Server device, configure the three address pools as intended.

 Indicate on the appropriate router interfaces where the DHCP server is located.

 Try to get dynamically IP addresses on each end device - Hosts .

 Use the PING command to communicate from each network to the Down device.

15 Mistakes Made During Network Configuration The chapter contains descriptions of the symptoms and causes of the most common mistakes when designing and configuring computer networks as well as ways to fix them.

15.1 Wiring or Port Errors

The figure below shows the incorrect use of cables and connecting the correct cable, but to the wrong port, for example, an Ethernet cable was connected to the RS232 console port.

Causes: a simple cable was used between the switches, the computer and router devices were connected to the switch using a patch cable, the computer was connected to the router using a straight cable.

Figure 15.1 Wrong cabling

Repair: switches should be connected using a patch cable, computer and router devices should be connected to the switch using a simple cable, the computer should be connected to the router using a patch cable.

Figure 15.2 Wiring condition after repair

Symptoms: The laptop cannot communicate with the router.

Cause: The correct cable is connected but to the wrong port, i.e. the Ethernet cable is connected to the RS232 console port.

Figure 15.3. Wrong port

Repair: remove the cable from the RS232 port, connect the cable again but to the Fast Ethernet port.

Figure 15.4. Condition after repair

15.2 Device Related Errors

PC0 is connected to the Switch0 switch. Switch0 is connected to Router0 . Why are the interface states on the Switch0 – Router0 connection disabled (red)?

Figure 15.5 Disabled port on router

Symptoms : PC0 cannot communicate with the router.

Cause: The Gig0/0 interface on the router is not enabled. Remember that interfaces are enabled by default on computers and switches, and disabled on routers. Therefore, you must manually enable the correct interfaces on your router.

Repair: Enable the Gig0/0 port on Router0.

Figure 15.6 Enabled port on the router

15.3 IP Addressing Errors

The figure below and the verbal description show incorrect IP addressing.

Figure 15.7 Wrong IP configuration on PC1

Symptoms: PC1 cannot communicate with the servers.

PC0 can ping any computer, and PC1 can only ping PC0. Why? The reason should be sought in the addressing of PC1- it can be the wrong IP address, the wrong default gateway or the wrong subnet mask, or for example the computer has been turned off. Cause: In this example, the error is caused by an incorrect default gateway setting. It is set to 10.0.0.2 and this is the address of the PC0.

Figure 15.8 Check your IP configuration

Repair: On PC1, set the gateway address to 10.0.0.3 (the interface address of the router to which the Switch0 is connected.

Figure 15.9 Topology fragment with correctly assigned the Default Gateway The next example shows incorrect IP addressing as well as the lack of a properly configured DNS service.

Symptoms: A request to view a page www.name.com from PC1's browser does not end with an error, the page does not appear.

Figure 15.10 Page request www.name.com ends with error When a PC1 user enters 20.0.0.2 into the browser, a page from Server1 is displayed.

Figure 15.11 Checking the page by IP address

However, when the PC1 user enters the address of the www.name.com the message "Host Name Unresolved" will be displayed.

Figure 15.12 Check a page using an HTTP address

The IP configuration is correct because all computers can communicate with each other, which is checked by ping. Server1 contains a website called www.name.com . The server address is 20.0.0.2. This server also acts as a DNS server.

Figure 15.13 Server1 IP Configuration

The IP addressing configuration for Server1 is correct.

Cause: PC1 does not know the DNS server address, or the DNS service is not enabled and configured correctly on Server1.

Figure 15.14 No DNS address for PC1

Figure 15.15 DNS address for PC1 set correctly

Fixed: After setting the correct DNS address (the correct address is 20.0.0.2 ) on PC1, the error described above still occurs. You must now check the DNS configuration on the server.

Figure 15.16 DNS status before repair

Fixed: To fix the error, enable DNS in Server1 and add an A-type record that contains the www.name.com name and the IP address assigned to that name 20.0.0.2 .

Figure 15.17 DNS status after repair

Then, on PC1, enter the address: www.name.com into the browser to check if the error has been fixed.

Figure 15.18 Check a page using an HTTP address

Symptoms: Communication between PC0, PC1 and Servver0, Server1 servers is not possible despite the correct configuration of the routing protocol. The following drawing and verbal description shows the incorrect IP addressing in the router interface.

Figure 15.19 Computers between two subnets cannot communicate The network works in the OSPF protocol in area 0. The configuration of the computers and OSPF has been validated and is correct. PC0, PC1 computers can communicate with each other. Server0, Server1 computers can communicate with each other. Computers from different subnets cannot communicate, e.g. PC1 cannot connect to Server1. Cause: In the example presented, the cause of the error is the incorrect setting of the interface address ( Gi0/1 ) on the RC router. It is set to 172.0.0.5 and this address is already used for the interface ( Gi0/0 ) in the RB router.

Fixed: To fix the error, set the correct address to 172.0.0.6 in the RC router for the Gi0/1 interface.

Figure 15.20 Topology after repair

16 List of the Samples and Skill Exercise’s Solutions This chapter contains a list of sample files and exercise solutions as an addition to the manual.

16.1 The Sample Solution Files

Table 16.1 List of the Sample Files

16.2 The Skill Exercise’s Solutions

Table 16.2 List of the Skill Exercise’s Solution Files