Re: [nsp] A question regarding BGP next-hop reachability.

From: George Robbins (grr@shandakor.tharsis.com)
Date: Sun Jun 17 2001 - 05:59:12 EDT


Well, reachable via the default gateway is a different statement than
there being a valid route to the next hop. You should arrange things
such that there is a valid route from your router to each of the
next-hops that the route-reflector can offer, at least the ones that
you want to listen to vs. default routing or bouncing thru the route
reflector.

                                                George

> From cisco-nsp-request@puck.nether.net Sun Jun 17 04:28:22 2001
> Resent-Date: Sun, 17 Jun 2001 04:28:15 -0400
> Received-Date: Sun, 17 Jun 2001 04:23:50 -0400
> X-Authentication-Warning: nvt.netvision.net.il: elijah owned process doing -bs
> Date: Sun, 17 Jun 2001 11:23:47 +0300 (IDT)
> From: Elijah Kagan <elijah@netvision.net.il>
> To: cisco-nsp@puck.nether.net
> Subject: [nsp] A question regarding BGP next-hop reachability.
> Resent-From: cisco-nsp@puck.nether.net
> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/6854
> X-Loop: cisco-nsp@puck.nether.net
> Precedence: list
> Resent-Sender: cisco-nsp-request@puck.nether.net
>
>
> Suppose there is a router (a Cisco router, of course) that learns nothing
> but a default gateway from its IGP. It also has an iBGP session with its
> default router and receives the full Internet routing table. The default
> router acts as a route-reflector.
>
> Now here is the problem. The next-hop of every BGP prefix it learns is
> reachable via IGP's default gateway, but for some reason it is not good
> enough, BGP marks it as inaccessible and disregards the prefix.
>
> This situation could appear in L1 router that learns a prefix originating
> form a different IS-IS area.
>
> Please advise....
>
> -- elijah
>
>
>



This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:42 EDT