[c-nsp] ospf nssa ibgp problem

[Gert Doering]

Hi,

On Mon, Oct 16, 2006 at 02:12:47PM -0400, Jon Lewis wrote:
> For some reason, iBGP (trying to send the 7206 full routes from a pair of 
> 7600's acting as route-reflectors) even with no synch on the 7206 isn't 
> working properly.  The 7206 receives ~200K routes, loads them into the 
> routing table (seen via show ip route sum), but then after less than a 
> minute, it flushes the BGP routes from the routing table.  The BGP 
> sessions remain up, and report ~200K routes received.  After a short 
> time, the 7206 repopulates the routing table with the ~200K BGP routes, 
> but then 30-40s later, it purges the table again.  The 7206 is running 
> c7200-k91p-mz.122-18.S12.bin.

Sounds as if the next-hop for the BGP routes isn't in the OSPF tables
the 7206 is receiving.  (Or, more specifically: there is a more-specific
next-hop in the BGP routes than in the OSPF routes, so BGP will come
up, will notice "ugh, I have recursive routes" [BGP route pointing to
BGP route pointing to the *same* BGP route], and will remove all the
prefixes again).

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