Re: [rmcat] RMCAT Testing Topology and Initial Testing

[Mirja Kuehlewind <[e-mail]>]

Hi Michael,

thanks you for writting this up. What is your plan with this document? Are you 
planning to merge this document with draft-singh-rmcat-cc-eval-02 or is this 
the starting point for an own draft?

Two comment on the document as an individual contributor:

1) Regarding the passing criteria we should be more careful. I believe you had 
already a certain solution in mind while writting the document. But in fact 
the solution does not have to be a pure delay based approach. Probability it 
actually will not be only delay based because we have to compete with 
standard TCP. 
More specifically regarding the criteria 2 (no packet loss): I don't think 
this is the right criteria as we only what to have a small (average) queue. 
If there e.g. is a little spike in the queue (maybe in the start-up phase of 
a competing flow) that might be toleratable. While the packet loss itself (if 
this is only a few packets) should not be a problem for the application.
Also regarding the capacity sharing: I don't see fair or equal sharing as a 
criteria; not even a sharing which is close to equal (as defined in criteria 
1). The thing that is important is that each flow gets at least some part of 
the capacity or maybe there is even something like a minimum rate each flow 
needs to achieve (as long as N * min_rate < link capacity). I guess it is 
probably the easiest solution to come up with an algorithm with achieves 
something like more or less equal sharing but it a too strong requirement (in 
case someone has a more fancy idea).
To sum up: when formulating evaluation criteria, we should not be more 
restrictive that the requirements in draft-jesup-rmcat-reqs.

2) This (simple) scenario is a good starting point but it only focuses on 
capacity sharing and small delays. There are many algorithm out there already 
which can fullfill these requirement (e.g. TCP Vegas). The main challenge we 
have to worry about is that we also need to compete with TCP. This is not 
handled at all in your document so far.

Mirja


On Friday 05 April 2013 18:54:19 Michael Ramalho (mramalho) wrote:
> RMCAT Design Team,
>
> At the RMCAT Design Team meeting on 28 March, I volunteered to document an
> initial network topology model and an initial testing methodology model for
> our RMCAT work. The goal is to have a topology and an associated testing
> methodology so that we  could determine if the RMCAT requirements are being
> met.
>
> Attached is my first draft for such a proposal. It is a work in progress.
>
> Comments are welcome, but please be sure to raise a technology-based
> objection and associated rationale with any item within it you find
> objectionable.
>
> We have our work cut out for us, as designing an acceptable control system
> (i.e. rate adaptation algorithm) to meet all of our requirements will be
> tough. As can be seen, my initial testing proposal only addresses the
> simplest part of our work: RMCAT self-friendliness.
>
> I would like to poll this audience, when should the next RMCAT design
> meeting be held?
>
> I would be willing to review various aspects of my proposal at the next
> meeting.
>
> Comments? Fire away!
>
> Best Regards,
>
> Michael Ramalho



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Dipl.-Ing. Mirja Kühlewind
Institute of Communication Networks and Computer Engineering (IKR)
University of Stuttgart, Germany
Pfaffenwaldring 47, D-70569 Stuttgart

tel: [phone]
email: [e-mail]
web: www.ikr.uni-stuttgart.de
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