[46228] in North American Network Operators' Group
Re: Survey on IBGP persistent route oscillation problem
daemon@ATHENA.MIT.EDU (Vincent Gillet)
Thu Mar 21 12:43:00 2002
Date: Thu, 21 Mar 2002 18:42:19 +0100
From: Vincent Gillet <vgi@zoreil.com>
To: Danny McPherson <danny@tcb.net>
Cc: nanog@merit.edu
Message-ID: <20020321174219.GC6854@opentransit.net>
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danny@tcb.net disait :
> > We have a similar situation (RR + always-compare-MED off), and the BGP table
> > version keeps changing at 1K/min (http://performance.cn.net:2003/). I
> > suspect some
> > route meet the criteria of IDR-oscillation draft. But in real world, it's
> > very hard to pick
> > up the pattern depicted in the draft from a huge log of debug bgp output.
>
> It's actually quite trivial to identify. Have a look at:
>
> http://www.cisco.com/warp/public/770/fn12942.html
As Yu said, it is not so easy.
Most of the output in "show ip route bgp | include , 00:00" command match
flapping updates that are getting "dampening candidates" !!
Beside, you have to run the command on a router that might hit the
problem .... it depends a lot on your peering locations and partners.
If you run Cisco commands on wrong router, you would not see any
problem and may get in wrong conclusion !!
> > 2. From my experience, most flapping seems to be oscillation route
> > which escaped the eBGP damping protection. And for this, we need
> > adjust damping parameters from RIPE 220 to make up.
>
> Nope. Dampening doesn't resolve this because it occurs
> intrA-domain.
Does not fix, but it would lower updates thus help to identify
update loops.
Vincent.
