Peer Groups
When working with BGP, you will find
that many routers require the same neighbor
statements in their configurations. No matter what kind of routing
policy you’re implementing and how you’re implementing
it, if you want the same policy lists applied to a group of neighbors
you’ll end up giving the same parameters on all the
neighbor
statements. This process can be
error-prone and confusing.
Peer groups eliminate redundant configuration lines by allowing you to define a group and then make each neighbor a part of that group. For example, assume that you have a route map that enforces some routing policy. Instead of applying that route map separately on each neighbor, you can add all the neighbors to a peer group and then apply the route map for the group as a whole.
In Figure 10-3, we have a network (AS 500) with
three BGP routers. Instead of defining the same route maps for each
neighbor in Router 1’s configuration, we create a peer group
called policy1
. This peer group defines the
non-unique configuration items. We then make Router 2 and Router 3
members of this peer group. Here is the BGP configuration for Router
1:
router bgp 500 ! Define our peer group and apply the configuration items to it neighbor policy1 peer-group neighbor policy1 remote-as 500 neighbor policy1 next-hop-self neighbor policy1 route-map map1 in ! Now define our neighbors as part of peer group policy1 neighbor 10.10.2.1 peer-group policy1 neighbor 10.10.3.1 peer-group policy1
Figure 10-3. iBGP network ...
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