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Harmen,
Please see my comments below. Thanks for the interest.
Regards, Siamack
Harmen van As wrote:
Dear SiamackIt would
be necessary to back off your statements on the merits andperformance of
Open Loop with simulations.
> My statements are based on the protocol
flow charts & simulation of congestion avoidance algorithms conducted
so far. Please see slide #5 for the list of references.
The goal of MAC protocolsis also to
achieve fairness among iinterfering nodes, not merely congestioncontrol.
> It would be helpful to have a concise
description of this goal, what is fairness in this context, and what
interference you have in mind. I have shown that CA algorithms covered
can introduce HOL blocking which is a form of interference. Open loop congestion
controls do not do this.
The first two statements on
CA mechanisms is certainly not true at all.
> Again the references in slide #5,
& existing simulations show that the weighted fairness algorithms are
only targetting the low priority class i.e. C' portion of the ring bandwidth
(C'= C-a ).
This is what I call static partitioning.
>The delay bound that I have in mind
is due to the high priority traffic class only. i.e. the ring access delay
of the high priority traffic is only due to high priority traffic on the
ring. In some CA schemes and under certain conditions described in the
slides, the low priority traffic is interfering with this bound. i.e. low
priority ring traffic is scheduled ahead of high priority acess.
>Of course if one is patient enough
even best effort traffic would eventullay make it through. So we
have to be careful that we are on the same page with respect to delay bounds.
We will show that by two protocols
having different degrees of sophistication.Seems to become an interesting
and lively September meeting in San Jose.
> Looking forward to it.
Best regardsHarmen------------------------------------------------------------------
Prof.Dr. Harmen R. van As
Institute of Communication Networks
Head of Institute
Vienna University of Technology
Tel +43-1-58801-38800
Favoritenstrasse 9/388
Fax +43-1-58801-38898
A-1040 Vienna, Austria
http://www.ikn.tuwien.ac.at
email: Harmen.R.van-As@xxxxxxxxxxxx
------------------------------------------------------------------ORIGINAL
MESSAGETo: stds-802-17@xxxxxxxx
Subject:
[RPRWG] Merits of Open Loop
From: Siamack
Ayandeh <sayandeh@xxxxxxxxxx>
Date: Mon,
06 Aug 2001 11:01:39 -0400
CC: sayandeh@xxxxxxxxxx
Sender: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
Folks, As
some people are busy doing simulations and writing proposals for the
San Jose meeting, I am posting this
presentation early on the
reflector. It describes the
merits of open loop congestion controls and
may impact some of the simulation
scenarios that would be presented.
The main conclusions of the document
are that: - Congestion avoidance
algorithms may lead to static partitioning of the
ring bandwidth between high and low
priority traffic
- With CA it may not be possible to
bound the ring access delay of high
priority traffic
- Open loop does not suffer from HOL
blocking
- Open loop has relatively low configuration
and operational complexity
- Open loop is not prone to tuning
issues, or link aggregation, etc... Regards,
Siamack
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