Dampening considered harmful? (Was: Re: verizon.net and other email grief)
Jared Mauch
jared at puck.nether.net
Fri Dec 17 04:43:12 UTC 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 jared at puck.nether.net
clue++; | http://puck.nether.net/~jared/ My statements are only mine.
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