THEO 3013 Lecture Notes - Lecture 3: News Aggregator, Border Gateway Protocol, Ibm System I
Document Summary
The ebgp next-hop attribute is the ip address that is used to reach the advertising router. For ebgp peers, the next-hop address is the ip address of the connection between the peers. For ibgp, the ebgp next-hop address is carried into the local as. Router c advertises network 172. 16. 1. 0 with a next hop of 10. 1. 1. 1. When router a propagates this route within its own as, the ebgp next-hop information is preserved. If router b does not have routing information regarding the next hop, the route will be discarded. Therefore, it is important to have an igp running in the as to propagate next-hop routing information. external, it prefers the path that was received first (the oldest one. the bgp router with the lowest router id. If the originator or router id is the same for multiple paths, it prefers the path with the minimum cluster list length.
