BGP Configuring Peer Groups

You will often want to apply the same policies to most or all of the peers of a particular BGP speaker.
Update policies are usually defined by route maps, filter lists, and distribution lists.

You can reduce the configuration effort by defining a peer group made up of these peers.

A peer group is defined relative to a particular BGP speaker. Two peer groups, eastcoast and leftcoast.
Each of these peer groups is defined for router Chicago, the hub router. Routers Boston, NY, and Miami
have no knowledge of being members of Router Chicago’s eastcoast peer group.

Similarly, routers SanFran, LA, and SanDiego have no knowledge of being members of router
Chicago’s leftcoast peer group.

The following commands configure the eastcoast peer group on router Chicago:

host1(config)#route-map wtset permit 10
host1(config-route-map)#set weight 25
!
host1(config)#router bgp 23
!
host1(config-router)#neighbor eastcoast route-map wtset in
!
!
!
host1(config-router)#neighbor eastcoast peer-group
!
host1(config-router)#neighbor 10.6.6.2 remote-as 12
host1(config-router)#neighbor 10.6.6.2 peer-group eastcoast
!
host1(config-router)#neighbor 10.7.3.2 remote-as 12
host1(config-router)#neighbor 10.7.3.2 peer-group eastcoast
!
host1(config-router)#neighbor 10.4.4.2 remote-as 12
host1(config-router)#neighbor 10.4.4.2 peer-group eastcoast

!
!

The following commands configure the leftcoast peer group on router Chicago:

host1(config-router)#neighbor leftcoast peer-group
!
host1(config-router)#neighbor 10.3.3.2 remote-as 78
host1(config-router)#neighbor 10.3.3.2 peer-group leftcoast
!
host1(config-router)#neighbor 10.3.2.2 remote-as 2143
host1(config-router)#neighbor 10.3.2.2 peer-group leftcoast
!
host1(config-router)#neighbor 10.3.1.2 remote-as 136
host1(config-router)#neighbor 10.3.1.2 peer-group leftcoast

neighbor peer-group

Two versions of this command exist. Use to create a BGP peer group or to configure
a BGP neighbor to be a member of a peer group.
!
To create a BGP peer group, specify a peerGroupName for the new peer group.
!
To assign members to a peer group, specify an ip-address and a peerGroupName
of a BGP neighbor that belongs to this group.
!
Most of all :
This command takes effect immediately.