source: Petr Lapukhov Abstract This publication briefly covers the use of 3rd party next-hops in OSPF, RIP, EIGRP and BGP routing protocols. Common concepts are introduced and protocol-specific implementations are discussed. Basic understanding of the routing protocol function is required before reading this blog post. Overview Third-party next-hop concept appears only to distance vector protocol, or in the parts of the link-state protocols that exhibit distance-vector behavior. The idea is that a distance-vector update carries explicit next-hop value, which is used by receiving side, as opposed to the “implicit” next-hop calculated as the sending router’s address – the source address in the IP header carrying the routing update. Such “explicit” next-hop is called “third-party” next-hop IP address, allowing for pointing to a different next-hop, other than advertising router. Intitively, this is only possible if the advertising and receiving router are on a shared ...