BGP Next-Hop Processing:
- For eBGP peers: Change next hop address on advertised routes.
- For iBGP peers: Do not change next hop address on advertised routes.
This can result in BGP routes being advertised where the next hop is unreachable so the neighbor does not populate the routing table with routes from BGP. It is resolved by using “next-hop-self” command on the router advertising the external BGP routes to the iBGP neighbor:
router bgp 5500
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 5500
neighbor 1.1.1.1 update-source Loopback4
neighbor 1.1.1.1 next-hop-self
