North American Network Operators Group

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Re: Dampening considered harmful? (Was: Re: and other email grief)

  • From: Jared Mauch
  • Date: Thu Dec 16 23:44:27 2004

On Fri, Dec 17, 2004 at 12:42:21AM +0100, Iljitsch van Beijnum wrote:
> On 17-dec-04, at 0:21, Jerry Pasker wrote:
> >>	ie: does dampening cause more problems than it tries to solve/avoid
> >>these days.
> >I don't know what takes more router resources;  dampening enabled 
> >doing the dampening calculations, or no dampening and constantly 
> >churning the BGP table.  I would assume dampening generally saves 
> >router resources, or operators wouldn't chose to enable it.
> One reason to be careful with dampening is that flaps can be 
> multiplied. (Connect to routeviews and see the different flap counts 
> under different peers for the same flap at your end to observe this.)

	There have been numerous people who have spoken and released
research on this topic.

	I think with the "better" routing code out there these
days, that most people can quickly handle a large number
of next-hop changes, etc.. in their hw/sw that disabling dampening
would allow the networks to reconverge fairly quickly without (much)
trouble.  (going to respond to the streaming video/audio/whatnot
issue seperately).

	- jared

Jared Mauch  | pgp key available via finger from [email protected]
clue++;      |  My statements are only mine.