From: Michael Whittle (mgwhittle@gmail.com)
Date: Wed Jul 02 2008 - 17:38:55 ART
Hi all,
I wonder if you can help me.
I have an OSPF problem and a little stuck. I have an MPLS network with
multiple spoke VPN's. I have a Cisco ASA5510 connected to a PE with a trunk.
Each VPN connects on it's own VLAN. Each connection between the ASA and the
PE is running OSPF area 0. The ASA only advertises a default route and a
couple of other routes to each MPLS VPN spoke. The spokes only advertise
their BGP routes into OSPF using a route-map to filter. Each connection to
the ASA is configured the same way and it's working perfectly except for one
of them.
For some reason the ASA is seeing routes flapping on one of them when the
configurations are identical and everything is shared. It seems to go in
about a 10 second interval. All routes received, then all routes lost. At
first I thought it must be a routing loop but usually when this happens you
would see the routes changing rather than flapping. OSPF is stable and the
neighbor is up. I'm not seeing anything nasty in the logs. If I add static
routes on the ASA towards the VPN then it's stable so that rules out the BGP
routes having issues. My question is what could cause this sort of behavior
where the routes appear and disappear in cycles like this? Is there anything
I can check or any useful debugs I can try? I tried "debug ip ospf adj",
"debug ip ospf spf" and "debug ip ospf events" and none of them show
anything useful.
I would have thought if there was a problem with OSPF the adjacency would be
flapping as well. If it was a routing loop surely I wouldn't see the route
leave all together just the next-hop be updated by other device. So I'm just
trying to work out what else it could be. I would really appreciate some
tips on what I could try.
Thanks in advance.
Cheers,
Mike
This archive was generated by hypermail 2.1.4 : Mon Aug 04 2008 - 06:11:53 ART