BGP Configuration Using Peer Group

Peer group in a set of BGP neighbor that share some policy.  Policy that can be the same, for example, route-map, filter-list, prefix-list, update-source, route-reflector client.  Peer group can reduce cpu process consumption, also configuration effort.


Example

BGP Configuration Using Peer Group In Cisco Router

Before using Peer Group

router bgp 65000
neighbor 10.10.1.1 remote-as 65000
neighbor 10.10.1.1 update-source loopback0
neighbor 10.10.1.1 route-reflector client
neighbor 10.10.1.1 next-hop self
neighbor 10.10.1.2 remote-as 65000
neighbor 10.10.1.2 update-source loopback0
neighbor 10.10.1.2 route-reflector client
neighbor 10.10.1.2 next-hop self

After using Peer Group

router bgp 65000
neighbor INTERNAL-PEER peer-group
neighbor INTERNAL-PEER update-spurce loopback0
neighbor INTERNAL-PEER route-reflector client
neighbor INTERNAL-PEER next-hop self
neighbor 10.10.10.1 remote-as 65000
neighbor 10.10.10.1 peer-group INTERNAL-PEER
neighbor 10.10.10.2 remote-as 65000
neighbor 10.10.10.2 peer-group INTERNAL-PEER

BGP Configuration Using Peer Group in Juniper Router

In JunOS, by default neighbor is create under group, a.k.a peer group.  So, if you want share policy, just apply policy under group, not under specific neighbor.