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Re: [tsvwg] Neal Cardwell's rationale for supporting ECT(1) as an input/L4S signal

Neal Cardwell <ncardwell@google.com> Tue, 12 May 2020 20:30 UTC

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From: Neal Cardwell <ncardwell@google.com>
Date: Tue, 12 May 2020 16:29:46 -0400
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To: Jonathan Morton <chromatix99@gmail.com>
Cc: Jeremy Harris <jgh@wizmail.org>, tsvwg IETF list <tsvwg@ietf.org>
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Subject: Re: [tsvwg] Neal Cardwell's rationale for supporting ECT(1) as an input/L4S signal
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On Fri, May 8, 2020 at 1:54 PM Jonathan Morton <chromatix99@gmail.com> wrote:
> The shallow queues referred to are intended for deployment in tightly
> controlled datacentre environments, where the typical path RTT is measured in
> microseconds rather than milliseconds. It would not be surprising if a
> transport passing through such a queue as part of a typical Internet path of
> many milliseconds experienced poor utilisation.

I think the issue is that such paths do not currently suffer from
throughput problems, but could if they attempt to participate in an
SCE conversation.

> But that, I think, should be
> taken as a misconfiguration of the network - one which SCE deals with
> identically to existing ECN transports.

I think that depends on what is included in "existing ECN transports".
If we include ECN transports like RFC8257/DCTCP, then SCE deals with
this scenario differently than such transports.

neal

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