BGP Peer Group and configuration

BGP Peer Group

By default, BGP updates are sent on a neighbor to neighbor basis and the result more CPU resources being used, also by implementing non-default settings for example performing filtering using prefix lists, route map, or filter list to those neighbors, even more CPU resources are consume.

When, many neighbors are having similar configuration parameters. Cisco IOS allows us to create logical group those similar neighbors into a BGP peer group then you apply your non-default BGP configuration to those parameters to each neighbor individually. Actually a single router can have multiple peer groups, each representing a separate set of parameters. The result less CPU resources required. Remember router still sends out individual BGP updates to each of its neighbors. It does require based on BGP characteristics of establishing a TCP session with each neighbor.

Inshort: BGP peer group means applying same policies to multiple neighbors.It’s useful when many neighbors have the same configuration parameter. updates are generated once per peer group.

lets see the configurations.
Topology:

• configure the topology as per the diagram and its interfaces.
• configure eigrp 100 all the routers to ensure the reachability between the loopbacks.
• configure loopback 0 to establishing peering, configure peer group name cisco.
• configure authentication and make sure all the peer should use same password.(in our topology we use internetworks)
• configure BGP version 4 and advertise LAN interfaces only.

https://www.internetworks.in/2018/11/bgp-peer-group-and-config.html