[c-nsp] BGP neighbor not establishing session

[Kenny Sallee]

On Sun, Nov 21, 2010 at 6:26 PM, Lobo <lobotiger at gmail.com> wrote:

> I've tried searching around for this problem but haven't found much info.
>
> We upgraded some 7301 routers the other night and there are a couple of
> neighbors which have not been able to re-establish themselves.  Debugging
> from one of the routers shows this:
>
> Nov 21 21:06:51.902 EST: BGP: Neighbor validation failed. Flags: 0x10,
> Neighbor-topo check: passed, Router ID: 172.29.1.1
> frorr01#
> Nov 21 21:07:00.098 EST: BGP: Neighbor validation failed. Flags: 0x10,
> Neighbor-topo check: passed, Router ID: 172.29.1.1
> frorr01#
> Nov 21 21:07:10.482 EST: BGP: Neighbor validation failed. Flags: 0x10,
> Neighbor-topo check: passed, Router ID: 172.29.1.1
> frorr01#
>
>
I've found this a great tool for working through BGP neighbor problems:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009478a.shtml#bgp_trouble_neighbor

<http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009478a.shtml#bgp_trouble_neighbor>Also
- some problems I've seen / had: incorrect BGP peer IP, ASN wrong, iBGP
loopback not reachable (is it in IGP?), ACL block tcp/179 things like that.
Not sure if any of this helps...

Kenny