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List:       quagga-users
Subject:    [quagga-users 11275] Odd problem - leak from OSPF into BGP
From:       Craig Miskell <craig.miskell () opus ! co ! nz>
Date:       2009-12-22 20:55:19
Message-ID: 4B313237.20909 () opus ! co ! nz
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Hi,
	I've seen an interesting problem on one of my routers running quagga 0.99.14.  After \
some work on some VLAN switch port  configurations which briefly interrupted some BGP \
sessions, I got the following:

aurt02# show ip bgp 10.0.56.1
BGP routing table entry for 10.0.56.0/22
Paths: (2 available, best #1, table Default-IP-Routing-Table)
   Not advertised to any peer
   Local
     192.168.249.207 from 0.0.0.0 (10.0.24.42)
       Origin incomplete, metric 10010, localpref 100, weight 32768, valid, sourced, \
best  Last update: Tue Dec 22 22:02:59 2009

   4771
     10.0.24.40 from 10.0.24.40 (172.18.51.204)
       Origin incomplete, localpref 100, valid, external
       Community: 4771:1003
       Last update: Wed Dec 23 09:33:10 2009

And:
aurt02# show ip route 10.0.56.1
Routing entry for 10.0.56.0/22
   Known via "ospf", distance 110, metric 10010, best
   Last update 11:45:15 ago
   * 192.168.249.207, via tun233


In this case, the route is and should be learned by both OSPF and BGP, but the (e)BGP \
learned route preferred because of  the default administrative distances of eBGP (20) \
vs OSPF (110).  What I can't figure out is why "show ip bgp 10.0.56.1"   displays the \
OSPF route, and as "Local", and thereby somehow preferred.

I took down the direct tunnel (tun233) and subsequently "show ip bgp 10.0.56.1" shows \
only the single true BGP route  from AS 4771, as I'd expect in the first place.  \
Bringing the tunnel back up didn't change that, so the problem is now  resolved.

My question:  Any idea how this happened in the first place?  Is it a fundamental \
misunderstanding on my part of what  "show ip bgp <prefix>" should be displaying, or \
have I triggered some sort of bug?

Thanks,
--
Craig Miskell
Senior Systems Administrator
Opus International Consultants
Phone: +64 4 471 7209
All children should be aptitude-tested at an early age and, if their main or
only aptitude is for marketing, drowned.
	-- David Canzi, news.admin.net-abuse.email, 2001-03-21

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