BGP Confederations

BGP Confederations provide another method of managing the number of IBGP mesh routes in an Autonomous System. To help reduce the number of peers a router will have in an Autonomous System, BGP employs the use of route reflectors. The routers peer with another router, or concentration router. These peers are then known as clients. They receive updates from and send updates to the route reflector.

The other networks see the confederation as a single AS. The sub-ASes, or mini-ASes, are transparent to the outside world. Similar to using route reflectors, this method reduces the number of IBGP mesh paths (see Figure D-9).

Figure D-9. BGP Confederation