[Iccrg] Delay as a metric of congestion

[Michael Welzl]

On Feb 21, 2010, at 11:12 PM, John Leslie wrote:

> Matt Mathis <mathis at psc.edu> wrote:
>>
>> John and I went around on this for a bit in a private conversation,
>> where I argued against his position.
>
>   I'm not positive what Matt "argued against," but it certainly wasn't
> my "position"...

although I did agree with what Matt wrote, it seems that
you really have a common base there:

>
>> Therefor: all stacks should include a secondary congestion control
>> mechanism that detects when they are causing large queues in the  
>> network
>> and regulates their congestion window accordingly.
>
>   I couldn't agree with that exact wording, but Matt & I may be close
> here. Perhaps:
> "
> " Stacks intending to "play nice" with TCP should implement a delay- 
> based
> " mechanism to avoid reaching a congestion level where packets they  
> send
> " are dropped instead of delivered. Research into such methods is an
> " appropriate field of study of the ICCRG.

... also in that I think my answer also applies to your statement,
I think: isn't that what LEDBAT is doing?

Okay, "research into such methods" is not exactly what LEDBAT
does, but it seems to me that the right way to start such research
would be an overview of current literature. There would be
quite a bit of overlap between such a literature overview and
what I'm writing (now together with David Ros) for LEDBAT.
We're going to submit the first "draft-ietf-ledbat.." version soon;
the previous version is:
http://tools.ietf.org/html/draft-welzl-ledbat-survey-00

I think that the very mechanism proposed in LEDBAT:
http://www.ietf.org/id/draft-ietf-ledbat-congestion-00.txt
might be a good candidate for what you propose above.

Cheers,
Michael