North American Network Operators Group

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Re: Survey on IBGP persistent route oscillation problem

  • From: Danny McPherson
  • Date: Thu Mar 21 11:39:25 2002

> We have a similar situation (RR + always-compare-MED off), and the BGP table
> version keeps changing at 1K/min ( 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:

Juniper syntax would result in the same..

> 1.  How many time do our operator really find and affected by the 
> problem depicted in  draft-ietf-idr-route-oscillation-01.txt

I know of more than a few, and would bet that if additional folks 
took the time to look, they'd realize it was occurring as well.

> 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

> 3.   Anyone see oscillation been magnified when injected 
> into RR (cluster structure) ?

Not sure I understand what you mean by "magnified"?

Have a look at the Cisco FN, it's useful in understanding and 
identifying the problem.