NEXT_HOP Reachability
Option 1 - Carry the R1 and R2 eBGP peering links in the IGP
Adds extra routes to the IGP
Carrying customer links adds instability to the IGP
Option 2 - Do “redistribute connected” and “redistribute static” into BGP on R1 and R2
Adds a LOT of extra routes to BGP. Connected subnets of any router with an eBGP peer are now carried in the IGP and BGP
Carrying customer links adds instability to BGP
BGP will know how to get to its BGP NEXT_HOPs via BGP. Illegal recursive lookups can easily led to severe route churn
Two recursive lookups have to be done to resolve the outbound interface. Traffic forwarding is not effected but troubleshooting multiple recursive lookups becomes complex