CompNtwk : Lab 4.3.4 Exploring Network QoS

Step 1: Cable and configure the network

a. Connect and configure the devices in accordance with the given topology and configuration.

Routing will have to be configured across the serial WAN link to establish data communications.

Configure Telnet access on each router.

b. Ping between Host1 and Discovery Server to confirm network connectivity.

1) Confirm Application Layer connectivity by telnetting from R2 to R1.

2) Troubleshoot and establish connectivity if the pings or Telnet fail.

c. After confirming the initial configurations, maintain a console terminal session connection with R2.

Step 2: Examine priority queue commands

Configuring Priority Queueing

Configuring priority queueing (PQ) has two required steps and an optional third step:

1. Define the priority list (Required)

2. Assign the priority list to an Interface (Required)

3. Monitor priority queueing lists (Optional)

A priority list contains the definitions for a set of priority queues. The priority list specifies which queue a

packet will be placed in and, optionally, the maximum length of the different queues. To perform queueing

using a priority list, you must assign the list to an interface. The same priority list can be applied to multiple interfaces. Alternatively, you can create many different priority policies to apply to different interfaces.

Defining the Priority List

The priority list is defined by:

1. Assigning packets to priority queues

2. Specifying the maximum size of the priority queues (Optional)

Packets are assigned to priority queues based on the protocol type and the interface where the packets enter the router. The priority-list commands are read in order of appearance until a matching protocol or interface type is found. When a match is found, the packet is assigned to the appropriate queue and the search ends. Packets that do not match other assignment rules are assigned to the default queue. The following global configuration mode commands are used to specify in which queue a packet is placed. The command format is priority-listlist-number Use a list-number of 1 and note the options available.

a. Enter the following command and note the options available.

FC-CPE-1(config)#priority-list 1 ?

default Set priority queue for

unspecified datagrams

interface Set priorities for packets

from a named interface

protocol priority queueing by protocol

queue-limit Set queue limits for

priority queues

b. Note some of the protocol options available.

FC-CPE-1(config)#priority-list 1 protocol ?

arp IP ARP

bridge Bridging

cdp Cisco Discovery Protocol

compressedtcp Compressed TCP (VJ)

http HTTP

ip IP

llc2 llc2

pad PAD links

pppoe PPP over Ethernet

snapshot Snapshot routing support

c. Note the IP protocol options available.

FC-CPE-1(config)#priority-list 1 protocol ip ?

high

medium

normal

low

d. Note the HTTP protocol options available.

FC-CPE-1(config)#priority-list 1 protocol http ?

high

medium

normal

low

e. Note the IP protocol high priority options available.

FC-CPE-1(config)#priority-list 1 protocol ip high ?

fragments Prioritize fragmented IP

packets

gt Prioritize packets greater

than a specified size

list To specify an access list

lt Prioritize packets less than a

specified size

tcp Prioritize TCP packets ‘to’ or

‘from’ the specified port

udp Prioritize UDP packets ‘to’ or

‘from’ the specified port<cr>

f. Note the IP protocol high priority TCP options available.

FC-CPE-1(config)#priority-list 1 protocol ip high tcp ?

<0-65535> Port number

domain Domain Name Service (53)

echo Echo (7)

ftp File Transfer Protocol (21)

ftp-data FTP data connections (20)

irc Internet Relay Chat (194)

nntp Network News Transport Protocol

(119)

pop3 Post Office Protocol v3 (110)

smtp Simple Mail Transport Protocol

(25)

telnet Telnet (23)

www World Wide Web (HTTP, 80)

Over 30 port/service options are available.

Step 3: Configure an example priority queue

From the global configuration mode, issue the following commands.

FC-CPE-1(config)#priority-list 1 protocol http high

FC-CPE-1(config)#priority-list 1 protocol ip normal tcp ftp

FC-CPE-1(config)#priority-list 1 protocol ip medium tcp telnet

What do these commands establish?

Sebuah daftar prioritas (nomor “1″) yang menetapkan paket HTTP yang akan ditandai sebagai prioritas tinggi, paket FTP rendah prioritas, dan Telnet paket sebagai prioritas menengah.

Step 4: Assign the priority list to an interface

a. From the global configuration mode, issue the following commands to assign the priority list to

interface serial 0/1/0.

FC-CPE-1(config)#int s0/1/0

FC-CPE-1(config-if)#priority-group 1

b. Confirm the priority list configuration. From the privileged EXEC mode, issue the show runningconfig

command.

Which statements in the configuration show that the priority list has been configured and applied

correctly?

interface Serial0/1/0

ip address 10.10.0.2 255.255.255.252

priority-group 1

priority-list 1 protocol http high

priority-list 1 protocol ip normal tcp ftp

priority-list 1 protocol ip medium tcp telnet

c. Confirm that issuing the show queueing priority command from the privileged EXEC mode

produces the following output:

FC-CPE-1#show queueing priority

Current DLCI priority queue configuration:

Current priority queue configuration:

List Queue Args

1 high protocol http

1 normal protocol ip tcp port ftp

1 medium protocol ip tcp port telnet

Step 5: Examine the priority queues operation

a. On Host1, launch a web browser and enter the URL http://172.17.1.1 to access the web

services configured on the server.

b. Use FTP to download a file. On Host1, launch a new web browser window and enter the URL

ftp://172.17.1.1, or from the command line issue ftp 172.17.1.1

c. Download a large file from the server; for example, the Thunderbird setup program file.

d. From the privileged EXEC mode, issue the following command:

FC-CPE-1#show queueing interface s0/1/0

Output similar to this should be displayed:

Interface Serial0/1/0 queueing strategy: priority

Output queue utilization (queue/count)

high/94 medium/0 normal/106759 low/0

Note the packet count for each queue:

High

Medium

Normal

Low

e. Initiate a Telnet session from R2 to R1 and issue some show commands on R1.

f. Close the Telnet session.

g. Issue the following command from the R2 privileged EXEC mode:

FC-CPE-1#show queueing interface s0/1/0

Note the packet count for each queue:

High

Medium

Normal

Low

What is the significant difference when compared to the previous output form this command in

Step 5d?

Antrian Menengah sekarang memiliki jumlah paket, ini adalah prioritas yang ditugaskan untuk paket Telnet.

Step 6: Determine the priority queue requirements for the case study

a. Using the FilmCompany case study, what would you expect the priority queue requirements to be?

b. Discuss and compare your priorities with other students.

c. Amend your priority list statements to include traffic associated with the proposed network upgrade.

Step 7: Clean up

Erase the configurations and reload the routers and switches. Disconnect and store the cabling. For PC hosts

that are normally connected to other networks (such as the school LAN or to the Internet), reconnect the

appropriate cabling and restore the TCP/IP settings.

Challenge

The following privileged EXEC command displays the contents of packets inside a queue for a particular

interface:

show queue interface-type interface-number

However, in this lab, it is not likely that sufficient data traffic was generated at one time for the interface

queues to hold packets long enough to be inspected. Discuss how a network has to be load tested to ensure that all traffic priorities are met.

 

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