Re: [tsvwg] Consensus call on ECT(1)

["Mohit P. Tahiliani" <[e-mail]>]

I would prefer Option 3, and the following is my view:

Besides the inter-protocol fairness tests that have been already discussed
in the list, I would suggest to extensively evaluate the intra-protocol
fairness of the proposed mechanisms. One of the tests for evaluating
intra-protocol fairness could be to consider a scenario where long lasting
flows are transmitting at rates that sum up to the link capacity, and the
buffer is below the marking threshold. Add new flows that are short lived
so that the buffer starts growing, and eventually the ECN marks begin to be
generated. We should then confirm that the long lasting flows back off
sufficiently to provide a fair share to the newly started short lived
flows, the queue control is as desired and the link capacity is fully
utilised. After the short flows end, let only the long lasting flows
operate for some duration, and then again add short lived flows. This test
could be repeated with varying RTTs for short flows in each epoch to
evaluate the proposals in scenarios with different feedback delays.

In my opinion, it is important to evaluate both the proposals (L4S and SCE)
in a realistic traffic model consisting of a mixture of long lasting flows
and short lived flows (the ones that do not last beyond the slow start
phase), and feedback delays ranging from a 100s of microseconds to 100s of
milliseconds.

I would suggest that we carefully outline the benchmark tests to
extensively evaluate the new proposals in terms of other desired metrics
and network scenarios.

Thanks and Regards,
Mohit P. Tahiliani

On Mon, May 4, 2020 at 11:45 PM Wesley Eddy <[e-mail]> wrote:

> *In this email thread, please state, concisely, which of the following
> viewpoints on ECT(1) you prefer. Please have extended discussion in a
> different thread. If you are uncomfortable sharing your opinion on the
> list, you may email the tsvwg chairs directly ([e-mail]
> <[e-mail]>). *
>
>
>
>
>
> * If you did not attend the 27 April interim, please watch the meeting
> video [https://www.youtube.com/watch?v=dw3YKyeFxQU
> <https://www.youtube.com/watch?v=dw3YKyeFxQU>] for context on this
> question. 1. I support using ECT(1) as an input signal to the network. This
> is the approach consistent with the current L4S drafts. This position does
> not mean that there are no remaining issues with L4S, but that the
> remaining issues can be resolved by continued WG effort on the current
> drafts. 2. I support using ECT(1) as an output signal from the network.
> This is consistent with SCE. If you believe L4S will not be safe for the
> internet without significant architectural changes, you are in this group.
> 3. There is a specific test or tests I need to see before making a decision
> about ECT(1). Please be specific about the tests in your response. Please
> submit your opinion by 5/18/2020. *
>
>