bgp client-to-client reflection

By default, a route reflector reflects routes received from its clients to its other clients. However, if a route reflector's clients have a full BGP mesh, the route reflector does not reflect to the clients. The bgp client-to-client reflection command enables client-to-client reflection for IPv4, IPv6, or IPv4 VRF routes, depending on the mode.

Route reflection can change the routes clients select. A route reflector only reflects those routes it selects as best routes. Best route selection can be influenced by the IGP metric of the route to reach the BGP next hop. Since a client's IGP distance to a given next hop may differ from the route reflector's IGP distance, a route reflector may not readvertise a route a client would have selected as best in the absence of route reflection. One way to avoid this effect is to fully mesh the clients within a cluster. When clients are fully meshed, there is no need for the cluster's route reflectors to reflect client routes to other clients within the cluster. When client-to-client reflection is disabled, a route reflector continues to reflect routes from non- clients to clients and from clients to non-clients.