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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical SUMMARY: Strange BGP phantom announce remaining
First, the problem disappeared because Colt cleared the router which was deceived by a bogus announce from Telecom Italia. Thanks. On Mon, Nov 12, 2001 at 03:16:14PM +0100, Stephane Bortzmeyer <[email protected]> wrote a message of 33 lines which said: > I probably made a stupid mistake when changing my BGP announces but I Apparently, I made no mistake. According to analysis done by Jim Cowie with data at http://gradus.renesys.com, the change was properly done. But at least one router in Telecom Italia did not receive it. There was nothing we could do, since it took place at a far away location. Without the action from Colt, we could have try to re-announce the more specific route for ten minutes (let it propagate), then to withdraw it again, hoping it will clear it. Next time, I'll try :-) > Does you have any idea why routers at Colt still see the old announce? The question should have been "Why routers at Telecom Italia corrupted Colt's database?". I received two hypothesis: >From the Telia support (very helpful, like the Abovenet one): >Cisco Bug Id CSCdt19638 : > >"BGP bestpath change not sent to peers > >Under rare circumstances, an updated Border Gateway Protocol (BGP) >bestpath may not be propagated to the BGP peers of a router. > >Workaround: Enter the clear ip bgp * soft out EXEC command to update >the peers with the current bestpath attributes." [The workaround did not work in our case, since it was not *our* router that send the wrong info.] >From Neil J. McRae at Colt: >We saw this route from a peer that was announcing us a huge number of >routes that for some reason max-prefix didn't prevent from happening, >although after rebooting, the box did take the session down. My guess >is that the routes announced to us had sometype of corruption that >didn't send it through the max-prefix subroutine properly to detect >the number of routes being advertised. Well, now it works, back to work. > Configuration: Debian "woody", Linux kernel 2.4.9, Zebra routing > software 0.91 and 0.92a (hence the copy to the Zebra Nice software, no problem :-)
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