From: Brian Dennis (brian@xxxxxx)
Date: Sat Feb 10 2001 - 19:18:16 GMT-3
Chuck,
There are three things that can cause one BGP route to be preferred over
another BGP route that has a higher local preference. The first would be
that the next-hop address is unreachable. As you know you must have a route
to the next-hop address. A default route doesn't count here. Second you
might have synchronization enabled (on by default) which means that you must
have an IGP route before you'll select that route in BGP. Third would be the
weight. It seems that the weight here is the same so that wouldn't come into
play.
You should do a "show ip route" on the next-hop address. This usually isn't
an issue for an eBGP route because 'most' next-hop addresses for eBGP routes
are directly connected routes. The exception here would be when you're doing
eBGP multihop. If you do have a route to the next-hop address of the iBGP
route then in your case it must be because of synchronization. Disable it,
do a "clear ip bgp *" and see if BGP selects the other route.
Good luck on your lab.
Brian Dennis
CCIE #2210 (R&S)(ISP/Dial)
CCSI #98640
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Chuck Larrieu
Sent: Saturday, February 10, 2001 11:41 AM
To: CCIE_Lab Groupstudy List
Subject: IP BGP table - sanity check
Anything seem untoward in the following excerpt from a BPB table ( show ip
bgp ) ?
( the mailer will probably trash the formatting. Each route has two
entries - one with a local preference blank, and the other with a local
preference of 1000 )
Network Next Hop Metric LocPrf Weight Path
*> 192.168.100.0 10.254.254.6 0 102 603
i
* i 10.254.254.13 1000 0 603 i
*> 192.168.101.0 10.254.254.6 0 102 603
i
* i 10.254.254.13 1000 0
603 i
*> 192.168.102.0 10.254.254.6 0 102 603
i
* i 10.254.254.13 1000 0
603 i
*> 192.168.103.0 10.254.254.6 0 102 603
i
* i 10.254.254.13 1000 0
603 I
based on the indications in the left hand columns, is this what you would
expect? It is not what I would expect.
The router in questions is in AS 405, and his buddy iBGP router in AS 405 is
sending in the local preference value via a route-map.
Chuck
A long shot at passing is better than no shot.
Right now that's all I got to get me through,
So I gotta believe!
( paraphrased from Kathy Baille / Baille and the Boys
a song from several years ago )
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