[c-nsp] BGP neighbor not establishing session

[Oliver Boehmer (oboehmer)]

> I've tried searching around for this problem but haven't found much
info.
> 
> We upgraded some 7301 routers the other night 

to which software?

> 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#
 
we've seen this once in an environment where the path/interface MTU
didn't match.. can you check the MTU on the interface(s) and the MSS
negotiated? TCP transaction debug might help..

	oli