[76594] in North American Network Operators' Group
Re: Dampening considered harmful? (Was: Re: verizon.net and other email grief)
daemon@ATHENA.MIT.EDU (Jared Mauch)
Thu Dec 16 23:43:39 2004
Date: Thu, 16 Dec 2004 23:43:12 -0500
From: Jared Mauch <jared@puck.nether.net>
To: Iljitsch van Beijnum <iljitsch@muada.com>
Cc: Jerry Pasker <info@n-connect.net>, nanog@merit.edu
In-Reply-To: <2142E85E-4FBC-11D9-B673-000A95CD987A@muada.com>
Errors-To: owner-nanog-outgoing@merit.edu
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 jared@puck.nether.net
clue++; | http://puck.nether.net/~jared/ My statements are only mine.
