Just a short article today on BGP Peer Groups. I’ve been using them while practice labbing for the CCIP exams, thought I’d toss up a short post.

BGP Peer Groups “reduce the load on system resources by allowing the routing table to be checked only once, and updates to be replicated to all peer group members instead of being done individually for each peer in the peer group.” (-Cisco.com) They can also greatly reduce administrative overhead. They’re somewhat self-explanatory, you specify a Peer Group for two or more neighbors, then apply config to the group instead of each individual neighbor. We’re going to use my CCIP topology, but we’ll just focus on the iBGP peers:

We see that all of our PE routers are running iBGP and they’re fully meshed. Let’s look at PE1′s config without Peer Groups:

router bgp 6500
 neighbor 6.6.6.6 remote-as 6500
 neighbor 6.6.6.6 update-source Loopback0
 neighbor 6.6.6.6 next-hop-self
 neighbor 7.7.7.7 remote-as 6500
 neighbor 7.7.7.7 update-source Loopback0
 neighbor 7.7.7.7 next-hop-self
 neighbor 8.8.8.8 remote-as 6500
 neighbor 8.8.8.8 update-source Loopback0
 neighbor 8.8.8.8 next-hop-self
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