North American Network Operators Group
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Re: Route Supression Problem

  • From: Iljitsch van Beijnum
  • Date: Wed Mar 12 14:07:00 2003 
On Wed, 12 Mar 2003, Danny McPherson wrote:

> > Dampening is done on the eBGP router where the route enters the AS, and,
> > unless I'm mistaken, per route/path and not per prefix. So the flapping
> > that ISP A sees from ISP B is a completely seperate thing from the
> > flapping that ISP A sees from its customer's customer as far as the
> > dampening algorithm is concerned.

> Nope.  It's per-prefix.

If that is the case then dampening is severely broken, because then a
router that receives a prefix over two paths will lose *both* if _one_
flaps.

In any case, it is done on the eBGP router receiving the prefix/route,
so unless the two ISPs in question peer using the same router as they
use to connect to Jack's AS, there still shouldn't be any flapping
multiplication. (Hm, unless that happened inside Jack's network...?)

Iljitsch