Lab 9.2.9 Peer Groups

Objective:

Configure a peer group to assign policies to a group of BGP neighbors that share the same update policies.

Scenario:

You are the Network Administrator for AS 300. Given a normal BGP configuration, AS 200 and 400 are receiving updates about network 10.0.0.0. You wish to do this in an efficient manor, so you decide to use a peer group. Use the peer group to filter updates about 10.0.0.0 into AS 200 and AS 400.

Tasks:

  1. Configure BGP on each router and advertise each LAN. Be sure to use 3.0.0.2 on Router C and 2.0.0.2 on Router A. Use the .1 addresses on Router B. Verify you have connectivity with the show ip bgp command and the extended ping command.
  2. The first step is to define the peer group. This is done with the following command:
  • RouterB(config)#Router BGP 300
  • RouterB(config-router)#neighbor EXTERNALMAP peer-group

**EXTERNAL MAP is the name of the peer group**

  1. Now we are going to apply a policy to the peer group. We are going to filter 10.0.0.0 updates with a distribute list that will apply to both neighbors. To do this, issue the following commands:
  • RouterB(config-router)#neighbor EXTERNALMAP distribute-list 1 out
  • RouterB(config-router)#neighbor 2.0.0.2 peer-group EXTERNALMAP
  • RouterB(config-router)#neighbor 3.0.0.2 peer-group EXTERNALMAP
  1. Don't forget to configure the access-list!!
  • RouterB(config)#access-list 1 deny 10.0.0.0 0.255.255.255
  • RouterB(config)#access-list 1 permit 0.0.0.0 255.255.255.255

Why did we set the distribute list to out?

  1. Telnet to Routers A and C. Issue the clear ip bgp * command and watch the BGP routing table rebuild.

Did network 10.0.0.0 show up in the BGP routing table?

In this lab we did not save a lot of work by using a peer group. Can you think of a situation where a peer group would simplify configuration?

  1. Save your configuration.