Re: Question on draft-seemann-quic-accurate-ack-ecn-00

[Vidhi Goel <[e-mail]>]

Hello Ingemar,

Having been implemented Prague myself, this is mainly to get more accuracy around doing increase for non-marked bytes during congestion avoidance. Currently, we have no way of knowing that as we only know that some N packets were not CE marked but we don’t know which ones. 

If you see the example that I added in the draft, with the change proposed, an implementor can exactly know which packet was received with which code point. This way,  one can map the packet to packet size at the sender and accurately  compute non CE marked bytes. This is quite useful to do more accurate increase for cwnd to stay closer to the link capacity without building any excessive queues.

It may look like the change has subtle impact but with a large number of flows sharing the bottleneck, it definitely has impact on how tightly we control the increase in queuing delay.

Happy to discuss this during IETF.


Thanks,
Vidhi

> On Mar 14, 2024, at 7:21 AM, Ingemar Johansson S <ingemar.s.johansson=[e-mail]> wrote:
> 
> Hi Marten + others
>  
> I read through the draft
> https://datatracker.ietf.org/doc/draft-seemann-quic-accurate-ack-ecn/
>  
> Given that this adds more complexity than the default ECN counters, could you elaborate a bit more around which partcular cases where it would be beneficial with your proposed ECN feedback?
>  
> Regards
> /Ingemar
> =================================
> Ingemar Johansson  M.Sc.
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