Internet Routing Architectures, Second Edition

Route Reflectors

In some Internet service provider (ISP) networks, the internal BGP mesh can become quite large (more than 100 internal BGP sessions per router), which strongly suggests that some new peering mechanism be implemented. The route reflector^[1] concept is based on the idea of specifying a concentration router to act as a focal point for internal BGP sessions. Multiple (client) BGP routers can peer with a central server (the route reflector), and then route reflectors peer with one another. Although the BGP rule states that routes learned via one IBGP speaker can't be advertised to another IBGP speaker, route reflection allows the route reflector servers to "reflect" routes as described later, thereby relaxing the IBGP full-mesh ...