[99087] in North American Network Operators' Group
Re: Congestion control train-wreck workshop at Stanford: Call for Demos
daemon@ATHENA.MIT.EDU (Stephen Stuart)
Wed Sep 5 07:55:39 2007
To: Sean Donelan <sean@donelan.com>
cc: nanog <nanog@merit.edu>
In-reply-to: Your message of "Tue, 04 Sep 2007 10:30:57 -0400."
<Pine.GSO.4.64.0709041029580.26977@clifden.donelan.com>
Date: Wed, 05 Sep 2007 11:54:27 +0000
From: Stephen Stuart <stuart@tech.org>
Errors-To: owner-nanog@merit.edu
> On Tue, 4 Sep 2007, Stephen Stuart wrote:
> >>> Operators are probably more interested in the "fairness" part of
> >>> "congestion" than the "efficiency" part of "congestion."
> >>
> >> TCP's idea of fairness is a bit weird. Shouldn't it be per-user, not
> >> per-flow?
> >
> > How would you define "user" in that context?
>
> Operators always define the "user" as the person paying the bill. One
> bill, one user.
It's easy to imagine a context where authentication at the application
layer determines "user" in a bill-paying context. Passing that
information into the OS, and having the OS try to schedule fairness
based on competing applications' "guidance," seems like a level of
complexity that adds little value over implementing fairness on a
per-flow basis. In theory, any such notion of "user" is lost once the
packet gets out on the wire - especially when user is determined by
application-layer authentication, so I don't consider 802.1X or the
like to be helpful in this instance.
> Its fun to watch network engineers' heads explode.
What if the person paying the bill isn't party to either side of the
TCP session?
Stephen
