[e2e] Is a control theoretic approach sound? (fwd)

Shivkumar Kalyanaraman shivkuma at ecse.rpi.edu
Thu Jul 31 09:40:31 PDT 2003

The papers referred to are at:

BTW, my overall comments were to counter the rhetorical question that 
forms the title of this thread. Control-theory folks need to be given 
credit where it is due.


---------- Forwarded message ----------
Date: Thu, 31 Jul 2003 10:31:00 -0400
From: John T. Wen <wen at cat.rpi.edu>
To: dpsmiles at turing.acm.org, wen at ecse.rpi.edu, arcak at ecse.rpi.edu
Cc: Shivkumar Kalyanaraman <shivkuma at ecse.rpi.edu>
Subject: Re: [e2e] Is a control theoretic approach sound? 


The papers that Shiv mentioned can be found at



John T. Wen
Department of Electrical, Computer, & Systems Eng.
Rensselaer Polytechnic Institute
Troy, NY 12180
wen at cat.rpi.edu

----- Original Message -----
From: <dpsmiles at turing.acm.org>
To: <wen at ecse.rpi.edu>; <arcak at ecse.rpi.edu>
Sent: Wednesday, July 30, 2003 10:58 PM
Subject: Re: [e2e] Is a control theoretic approach sound?

Could I request you for a copy of your Infocomm 2003 paper mentioned below?



Durga Prasad Pandey
Assistant Online Editor
ACM Crossroads

Original Message:
From: Shivkumar Kalyanaraman shivkuma at ecse.rpi.edu
Date: Wed, 30 Jul 2003 20:49:55 -0400 (EDT)
To: end2end-interest at postel.org, wen at ecse.rpi.edu, arcak at ecse.rpi.edu
Subject: Re: [e2e] Is a control theoretic approach sound?

The issue of considering delay robustness and several other
properties directly in a non-linear dynamic control theoretic framework
has been proposed by my control-theory colleagues John Wen and Murat Arcak
in their INFOCOM 2003 paper -- this framework is a superset of Kelly and
Low static optimization frameworks and linearized stability analyses.
Since my colleagues do not read this mailing list, please cc your
responses directly to them too.

It is becoming clear that basic dynamics and steady state behavior of
congestion control schemes are best understood at the "flow"
level in optimization frameworks; and "fine-tuning" of schemes can be done
at the "packet" level (eg: estimation robustness issues,
increase/decrease: AIMD etc, slow start, interaction with timeout/rtt
estimation etc). This "packet-level" dynamic behavior can be validated by
ns-2 simulations or implementation trials.

This is the essence of the approach of Kelly and Low frameworks and the
other generalized frameworks...

Shivkumar Kalyanaraman
Associate Professor, Dept of ECSE, Rensselaer Polytechnic Institute (RPI)
110, 8th Street, Room JEC 6003, Troy NY 12180-3590
Ph: 518 276 8979   Fax: 518 276 4403
WWW: http://www.ecse.rpi.edu/Homepages/shivkuma

A goal is a dream with a deadline -C. Knight

On Thu, 31 Jul 2003, Panos GEVROS wrote:

> ----- Original Message -----
> From: "Yunhong Gu" <ygu1 at cs.uic.edu>
> Subject: Re: [e2e] Is a control theoretic approach sound?
> > Well, I think to decide how "aggressive" the AI will be is not that
> > *simple* a problem :) It is not the more aggressive the better (even if
> > the per flow throughput is the only objective), right?
> agreed but only if you want to address the problem in its full generality
> ... if it is restricted to those areas of the (capacity,traffic) space
> the packet loss is in [0...7-8%] range (and AIMD is indeed relevant) since
> out of this range timeouts start becoming the norm) then it is
> *fairly*straightforward* to decide on AIMD parameters which provide
> outcomes (wrt individual connection perfromance -within limits obviously-
> and wrt capacity utilisation).
> > > ..in their case they know pretty much that the links they are using
> in the
> > > gigabit range and there are not many others using these links at the
> same time.
> > >
> >
> > But what if there are loss, especially continuous loss during the bulk
> > data transfer? No matter how large the cwnd is initially, it can
> > to 1 during the transfer, then the problem arise again.
> drastic measures (timeout, exponential backoff etc) will always need to be
> in place -
> I 'm saying that (at least in the first attempt)  it pays being optimistic
> (this is the idea underlying slow start anyway..)-  and in certain
> environments indeed more optimistic than the standard prescribes since
> is a-priori knowledge of the network path characteristics and even traffic
> conditions - which is the case when considering OCxx links connecting
> particle physics laboratories.
> this approach seems to me a lot simpler and (most likely) equally
> compared to elaborate control schemes which try to do better while trying
> hard to remain "friendly" at the same time.
> Panos

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