What is BGP Peer Group? | How to configure BGP Peer Group?
BGP Peer Group and config
https://www.internetworks.in/2018/11/...
By default, BGP updates are sent on a neighbor-to-neighbor basis and the result is more CPU resources being used, also by implementing non-default settings for example performing filtering using prefix lists, route maps, or filter lists to those neighbors, even more, CPU resources are consumed.
When many neighbors are having similar configuration parameters. Cisco IOS allows us to create a logical group of 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. As a result, fewer CPU resources are required. Remember router still sends out individual BGP updates to each of its neighbors. It does require based on BGP characteristics establishing a TCP session with each neighbor.