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Re: [rmcat] Review of draft-ietf-rmcat-scream-cc-01

Michael Welzl <michawe@ifi.uio.no> Sun, 19 July 2015 21:56 UTC

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From: Michael Welzl <michawe@ifi.uio.no>
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To: Zaheduzzaman Sarker <zaheduzzaman.sarker@ericsson.com>
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Cc: "Karen E. E. Nielsen" <karen.nielsen@tieto.com>, Ingemar Johansson S <ingemar.s.johansson@ericsson.com>, Mirja Kühlewind <mirja.kuehlewind@tik.ee.ethz.ch>, "rmcat@ietf.org" <rmcat@ietf.org>
Subject: Re: [rmcat] Review of draft-ietf-rmcat-scream-cc-01
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> On 19. jul. 2015, at 23.28, Zaheduzzaman Sarker <zaheduzzaman.sarker@ericsson.com> wrote:
> 
> 
> Hi Michael,
> 
> If my memory supports me then I remember you saying prioritization can be easily applied with schedulers at some points in your presentation at RMCAT previous IETF meetings.
> 
> But if you think you haven't then please accept my apologies.

Nono, I just didn't understand the sentence as you phrased it. Yes, I did say that. We also mention scheduling as another way to do it in the coupled-cc draft.
I think scheduling is fine if all trafic is multiplexed on the same 5-tuple and you therefore know it will always share the same bottleneck.

Our coupled-cc mechanism was made to make the code easier. This applies when you have situations with a shared bottleneck detection algorithm as input, to decide whether you're coupling or not. This is a dynamic decision, requiring the ability to turn the coupling on and off.

E.g., quickly going from:  one congestion controller, 3 flows are scheduled onto it   to: 3 congestion controllers, one per flow  ...
and back...
...is probably not an easy matter to implement. Turning our coupled-cc mechanism on and off is very easy.

But since this is all on one host only, I don't think we should strictly enforce any certain behavior.

Cheers,
Michael

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