[c-nsp] Very Weird Problem with BGP Peer Groups and iBGP

[Gert Doering]

Hi,

On Fri, Mar 18, 2005 at 04:04:01PM -0700, John Neiberger wrote:
> address of some of the *other* subinterfaces!! Freaking weird. That
> should never happen, should it? If next-hop-self is configured, the next
> hop should always be the directly connected interface, right? 

Chances are that it's the IP of the interface where the BGP update went
out through.  So if you had internal flaps as well, and due to backbone
redundancy, the iBGP session was routed over some *other* path, this 
might explain things.

A common approach is to use the routers' loopback addresses for iBGP:

  interface loopback 0
    ip addr a.a.a.a

  router BGP xxx
    neigh b.b.b.b remote-as xxx
    neigh b.b.b.b update-source lo0
    neigh b.b.b.b next-hop-self
    
gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de