[130297] in North American Network Operators' Group
Re: BGP next-hop
daemon@ATHENA.MIT.EDU (Smith W. Stacy)
Thu Sep 30 20:56:43 2010
From: "Smith W. Stacy" <stacy@acm.org>
In-Reply-To: <m239sqzzdk.wl%randy@psg.com>
Date: Thu, 30 Sep 2010 18:56:22 -0600
To: Randy Bush <randy@psg.com>
Cc: North American Network Operators Group <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.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.
>=20
> of course it was solved by
>=20
> ip route 147.28.0.0 255.255.0.0 42.666.77.11
>=20
> 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.=20
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
