Re: BGP next-hop

["Smith W. Stacy" <stacy () acm org>]

On Sep 30, 2010, at 3:37 PM, Randy Bush wrote:
> it seems it gets the bgp route for 147.28.0.0/16 and then can not
> resolve the next hop.  it would not recurse to the default exit.
>
> of course it was solved by
>
>    ip route 147.28.0.0  255.255.0.0  42.666.77.11
>
> but i do not really understand in my heart why i needed to do this.

Section 9.1.2.1 of RFC 4271 seems to address this. 

A few points from that section:
 - The BGP NEXT_HOP can not recursively resolve (directly or indirectly) through the BGP route.
 - Only the longest matching route should be considered when resolving the BGP NEXT_HOP.
 - Do not consider feasible routes that would become unresolvable if they were installed.

--Stacy