Packet Tracer Activity: Exploring Network QoS

Jaskaran Kalsi, 1st

October 2009

Introduction

Quality of Server (QoS) is a method of providing better service for selected traffic types over various types of

packet-switched networks. QoS provides a method for determining which traffic should be given priority on a

network segment. For this exercise your task will be to complete the configuration on the QoS_Router to use

QoS to mark EIGRP, Telnet, SSH, and HTTP traffic that exits interface Serial 0/0/0. The policy map that you will

apply sets the IP precedence field to 7 for critical packets (EIGRP), 5 for interactive packets (Telnet and SSH), and

3 for web traffic (HTTP). All other traffic is left as unmarked in the default group.

Important note: All device passwords are set to cisco

Objectives

Your task is to complete the network design; install various devices, complete the configuration, and monitor

the network for Quality of Service (QoS).

Familiarize your use of Packet Tracer and explore the QoS capabilities of version 5.2/

A full list of tasks detailing the configuration which must be applied has been developed and is available below.

Lab Topology

Once you have completed all network configurations, your topology should match the network shown below.

Tasks

Cable and Configuration

Please complete the below tasks to complete the physical design of the network…

1. Drag and drop a PC onto the physical work space in Packet Tracer. Install this PC connecting to

“QoS_Router” port Fa0/0. Label this PC “Host 1”. Apply the following configuration:

a. IP Address - 10.1.1.200

b. Subnet Mask - 255.255.0.0

c. Default Gateway - 10.1.1.1

2. Drag and drop another PC onto the physical work space in Packet Tracer. Install this PC connecting to

“R3” port Fa0/0. Label this PC “Host 2”. Apply the following configuration:

a. IP Address - 200.200.200.20

b. Subnet Mask - 255.255.255.0

c. Default Gateway - 200.200.200.1

Configuration

Please complete the below step to configure ‘QoS_Router’ for packet marking…

Step 1: Apply the following configuration to create a class-map which marks all eigrp packets as critical:

QoS_Router(config)#class-map match-all critical

QoS_Router(config-cmap)#match protocol eigrp

Step 2: QoS_Router has been preconfigured with a policy map named ‘markingpolicy’. You need to apply the

following configuration to create the precedence level for the class-map which you have just created:

QoS_Router(config)#policy-map markingpolicy

QoS_Router(config-pmap)#class critical

QoS_Router(config-pmap-c)#set precedence 7

Step 3: You have now completed the steps to configure a class-map marking all eigrp packets as critical and you

have also set the precedence level to 7. The next task is to apply the policy-map which you have created onto

an interface. In this case the policy-map will be applied to S0/0/0 of QoS-Router, hence all interesting traffic will

be marked as it passes through:

QoS_Router(config)#interface s0/0/0

QoS-Router(config-if)#service-policy output markingpolicy

Test Packet Marking

In order to ensure that the configuration applied is functioning as required, it is important to test the network

for Quality of Service.

Firstly, issue the show policy-map interface serial0/0/0 command on QoS_Router. You should expect to see an

output as follows:

Since Telnet traffic is set

to be marked, and as yet

no interesting traffic has

been detected, no

packets have been

marked.

Important Note:

Since there has been no

web (http) traffic sent,

no packets have been

detected or marked.

Use the Simulation mode to observe the packet forwarding. The QoS stamps on EIGRP packets and Telnet

packets have different colours since they're marked with different precedence. ICMP packets don't have the

QoS stamps on them since they don't match the QoS match protocol list.

Now generate some interesting traffic by attempting to Telnet from Host 1 to Router R3 (172.16.23.3) within

Simulation Mode:

Note that all passwords on routers are set to cisco. Once a successful Telnet session has been initiated, exit the

session and return back to the QoS_Router.

Again, issue the command show policy-map interface s0/0/0 on QoS_Router, observe the output.

By activating the ‘Simulation Mode’ of QoS_Router, you should be able to see the various types of packets

travelling across the network. By default, you should see many EIGRP packets being exchanged between the

routers. With Telnet, visually you should also see Telnet packets being sent across the network; however,

observing closely within the ‘Event List’ you should be able to see the TCP authentication handshake packets as

well as Telnet packets.

Looking further in detail at the QoS_Router, once interesting traffic has been generated, you should see the

values of ‘marked packets’ increase.

Since Telnet traffic is set

to be marked, and

possesses a precedence

value of 5, the output

shows that Telnet

packets have been

marked.

Congratulations you have now successfully completed the Packet Tracer Activity!

Upon completion you have successfully completed the following objectives…

1. To use and work with the Packet Tracer v5.2 GUI.

2. Be able to select appropriate devices & network media and place it within the Packet Tracer work area.

3. Successfully connect the devices to create a LAN.

4. Configure wired PC’s to connect to a LAN and communicate with routing devices.

5. Apply network QoS marking traffic techniques.

6. Monitor network traffic using Packet Tracer’s Simulation Mode.

7. Generate interesting traffic within a network.

8. Identify QoS marked traffic.

We hope you enjoyed the activity and gained a valuable insight into the functions of Packet Tracer.

Why not try this in your laboratory as a student learning exercise?

Comments/queries are most welcome; please contact….

Jaskaran Kalsi

Assoc. Technical Manager

Europe & Central Eastern Europe

jkalsi@cisco.com