Peer Group
A peer group is a set of peers with the same policies. When a peer joins a peer group, it inherits the configurations of the peer group. If the configurations of the peer group change, the configurations of all the peers in the group changes accordingly.
On a large-scale BGP network, there are many peers and most of them need the same policies. Therefore, some commands need to be run repeatedly on each peer. Configuring a peer group can simplify the configuration.
Each peer in a peer group can be configured with unique policies to advertise and receive routes.