Lab 10.2.5: Priority Queuing

Objective:

  • To prioritize traffic between the WestCoast router and the EastCoast router, using priority queuing.

Scenario:

Our company has given us the task of connecting our east coast office with the west coast office via ISDN. It has been determined that we need to have a strict queuing policy for traffic going across this link. Certain traffic should have a higher priority than other traffic. We have decided that all TCP traffic should have high priority, ICMP traffic should have medium priority, all UDP traffic should have low priority, and all other traffic should have normal priority. It is our responsibility to connect these two routers together and configure priority queuing correctly.

Lab Tasks:

  1. Cable the lab as shown in the diagram.

  2. The first router to be configured is the WestCoast router. Log into the router and enter global configuration mode.
  3. Configure the following basic information into the WestCoast router:

    • Configure the hostname WestCoast on the router.
    • Configure the router to prevent the lookup of misspelled words.
    • Configure IGRP routing with the AS# 777. Ensure that no routing updates will be sent out of interface BRI 0.

    What is the command to prevent routing updates?

    • Configure the enable password to be cisco.
    • Configure the Ethernet 0 interface with the IP address 10.100.100.1/24.

     

  4. The next step is to configure the ISDN BRI connection on the WestCoast router from the global configuration:

    • Configure the ISDN switch type to be National ISDN-1.
    • Configure the username and password of the router to be dialed, the username should be EastCoast, and the password should be cisco.

    What is the command to set the username and password?

    • Configure the dialer list to permit IP traffic.
    • Since the routers are not sharing routing tables, we need to configure a static route to the EastCoast router. The IP address of the EastCoast network is 10.30.30.0/24 and the IP address to the router is 10.200.200.2/24.

     

  5. We are going to be using dialer profiles in this lab, so the final part of the basic configuration of the WestCoast router is to configure the BRI interface and dialer interface.

    • Configure the BRI interface with the IP address 10.200.200.1/24.
    • Configure the Service Profile Identifiers: SPID1=51055512340001, SPID2=51055512350001
    • Configure the encapsulation type to be PPP.
    • For security reasons, configure the authentication to be CHAP.
    • To keep the line from staying connected all of the time, configure the idle timeout to be 60 seconds.
    • Apply the dialer list to the interface

    At what router prompt should you enter the idle timeout command?

    • Lastly, the router needs to know where to dial. Configure the dialer map with the IP address of the EastCoast router(10.200.200.2), the name of the router to be dialed(EastCoast), and the number to dial(5558000).
  6. Next, Configure the following basic information into the EastCoast router:

    • Configure the hostname EastCoast on the router.
    • Configure the router to prevent the lookup of misspelled words.
    • Configure IGRP routing with the AS# 777. Ensure that no routing updates will be sent out of interface BRI 0.
    • Configure the enable password to be cisco.
    • Configure the Ethernet 0 interface with the IP address 10.30.30.1/24.
  7. The next step is to configure the ISDN BRI connection on the EastCoast router from the global configuration:

    • Configure the ISDN switch type to be National ISDN-1.
    • Configure the username and password of the router to be dialed, the username should be WestCoast, and the password should be cisco.
    • Configure the dialer list to permit IP traffic.

    What is the dialer list command to permit IP traffic?

    • Since the routers are not sharing routing tables, we need to configure a static route to the WestCoast router. The IP address of the WestCoast network is 10.100.100.0/24 and the IP address to the router is 10.200.200.1/24.



  8. The final part of the basic configuration of the EastCoast router is to configure the BRI interface and dialer interface.

    • Configure the dialer interface with the IP address 10.200.200.2/24.
    • Configure the Service Profile Identifiers: SPID1=51055580000001, SPID2=51055580010001
    • Configure the encapsulation type to be PPP.
    • For security reasons, configure the authentication to be CHAP.
    • To keep the line from staying connected all of the time, configure the idle timeout to be 60 seconds.
    • Lastly, the router needs to know where to dial. Configure the dialer map with the IP address of the WestCoast router(10.200.200.1), the name of the router to be dialed(WestCoast), and the number to dial(5551234).
    • Apply the dialer list to the interface.

    Don't forget the no shutdown command on the interfaces.


  9. Before configuring Priority Queuing on the routers, test your configurations by pinging the other router. This way you are insuring that your basic configuration is correct before changing it.

  10. Verify current queueing method in use

    • Enter the show interfaces command.

    In the information returned by the router, what does the router say the queueing method is for BRI interface?


  11. Configure Priority Queuing on both the WestCoast, and the EastCoast routers. We have determined, based on the applications in use, that TCP traffic should have a high priority, ICMP should have a medium priority, UDP should have a low priority, and all others should have a normal priority. Priority lists differentiate priorities based on interface, port specific protocols, or by protocol based on an access list. We will use the priorities according to protocol based on an access list in order to get all of the ports used by TCP, UDP, and ICMP. Our first step will be to configure extended access lists to allow TCP, UDP, and ICMP access for our priority lists. We will use the following commands to set up our access lists.

    WestCoast(config)#access-list 111 permit tcp any any
    WestCoast(config)#access-list 112 permit icmp any any
    WestCoast(config)#access-list 113 permit udp any any
    EastCoast(config)#access-list 121 permit tcp any any
    EastCoast(config)#access-list 122 permit icmp any any
    EastCoast(config)#access-list 123 permit udp any any

    Note: We are using different access list numbers on the different routers to help differentiate between the routers, but could have used any valid extended ip access list number(100-199).

  12. Once we have configured the access lists, we need to configure our priority list for each of the routers. The priority list should be according to the importance of the traffic, as stated previously. The following commands will be used to configure the router:

    WestCoast(config)#priority-list 1 protocol ip high list 111
    WestCoast(config)#priority-list 1 protocol ip medium list 112
    WestCoast(config)#priority-list 1 protocol ip low list 113

    EastCoast(config)# priority-list 2 protocol ip high list 121
    EastCoast(config)# priority-list 2 protocol ip medium list 122
    EastCoast(config)# priority-list 2 protocol ip low list 123

    Note: We are using different priority list numbers on the different routers to help differentiate between the routers, but could have used any valid priority list number.

  13. The next step is to assign a default queue. It is for all other traffic which has not yet been given a priority. From our initial findings, we have decided that all other traffic should have a normal priority. Here are the commands for a default queue.

    WestCoast(config)#priority-list 1 default normal
    EastCoast(config)#priority-list 2 default normal

  14. The final step in configuring our priority queuing list is to apply the list to an interface. Since our WAN interface is where we want to prioritize traffic, we will be applying it to the BRI 0 interface and dialer interface on each of the routers as follows:

    WestCoast(config)#interface bri 0
    WestCoast(config-if)#priority-group 
    WestCoast(config)#interface dialer1
    WestCoast(config-if)priority-group
    EastCoast(config)#interface bri 0
    EastCoast(config-if)#priority-group 2
    EastCoast(config)#interface dialer1
    EastCoast(config-if)priority-group 2

  15. Now, we need to check to make sure that the routers are using priority queuing and that it is operating correctly. Issue the following commands and observe the responses from the router.

    WestCoast#show queueing int bri0
    EastCoast#show queueing int bri0

    What did the routers respond with?

    WestCoast#show queueing priority
    EastCoast#show queueing priority

    What did the routers respond with?


  16. Optional challenge step to test the operation of PQ. From the workstation/server connected to the WestCoast router, initiate a large file transfer from the workstation/server connected to the EastCoast router. Now initiate a continuous ping from EastCoast workstation to the WestCoast workstation. Finally initiate a telnet session between the two workstations/servers. Enter show queueing interface bri 0 priority command on each of the routers.

What did the router respond with?

How has this response changed from the first time that you issued the show queueing interface bri 0 command?


Change the priorities so that they are in the reverse order UDP high…TCP low and retry the test as described previously. Enter show queueing priority command on each of the routers.

What did the router respond with?

How has this response changed from the first time that you issued the show queueing priority command?