[98708] in North American Network Operators' Group
Re: Extreme congestion (was Re: inter-domain link recovery)
daemon@ATHENA.MIT.EDU (Fred Baker)
Thu Aug 16 00:46:23 2007
In-Reply-To: <Pine.GSO.4.64.0708152209030.6329@clifden.donelan.com>
Cc: nanog <nanog@merit.edu>
From: Fred Baker <fred@cisco.com>
Date: Wed, 15 Aug 2007 21:40:21 -0700
To: Sean Donelan <sean@donelan.com>
Errors-To: owner-nanog@merit.edu
On Aug 15, 2007, at 8:39 PM, Sean Donelan wrote:
> Or would it be better to let the datagram protocols fight it out
> with the session oriented protocols, just like normal Internet
> operations
>
> Session protocol start packets (TCP SYN/SYN-ACK, SCTP INIT, etc)
> 1% queue
> Everything else (UDP, ICMP, GRE, TCP ACK/FIN, etc) normal queue
>
> And finally why only do this during extreme congestion? Why not
> always
> do it?
I think I would always do it, and expect it to take effect only under
extreme congestion.
On Aug 15, 2007, at 8:39 PM, Sean Donelan wrote:
> On Wed, 15 Aug 2007, Fred Baker wrote:
>> So I would suggest that a third thing that can be done, after the
>> other two avenues have been exhausted, is to decide to not start
>> new sessions unless there is some reasonable chance that they will
>> be able to accomplish their work.
>
> I view this as part of the flash crowd family of congestion
> problems, a combination of a rapid increase in demand and a rapid
> decrease in capacity.
In many cases, yes. I know of a certain network that ran with 30%
loss for a matter of years because the option didn't exist to
increase the bandwidth. When it became reality, guess what they did.
That's when I got to thinking about this.
