Weighting of paths with use of the weight attribute, which is unique to the Cisco IOS BGP implementation. Weighting is used in the path selection process when there is more than one possible route to a destination. If there are multiple paths to the same destination, weight can be used to define preference for one over the others. When the preferred path goes away, the next preferred path is used. The initial data-flow across a BGP backbone makes up the entire BGP routing table.
Routers send incremental updates as the routing tables change.
To ensure that connections are still up, routers periodically send keepalive messages. Before it exchanges information with an external AS, BGP ensures that networks within the AS are reachable. By reducing the number of BGP neighbors, this capability decreases the amount of BGP processing that routers must do. One method of avoiding the need for BGP peering is to set up a route reflector, which allows a BGP node to act as a passalong or reflector of traffic between two or more other nodes. This approach limits the need for full-mesh configurations to within the subautonomous systems themselves.