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Re: [tsvwg] L4S and the detection of RFC3168 AQMs

Bob Briscoe <ietf@bobbriscoe.net> Mon, 15 February 2021 17:17 UTC

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To: "alex.burr@ealdwulf.org.uk" <alex.burr@ealdwulf.org.uk>
Cc: Martin Duke <martin.h.duke@gmail.com>, "tsvwg@ietf.org" <tsvwg@ietf.org>
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From: Bob Briscoe <ietf@bobbriscoe.net>
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Date: Mon, 15 Feb 2021 17:17:23 +0000
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Subject: Re: [tsvwg] L4S and the detection of RFC3168 AQMs
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Alex,

On 15/02/2021 11:23, alex.burr@ealdwulf.org.uk wrote:
>>    If that is the case (and the WG accepts it) then there are no false positives at startup. The only reason then  to worry about the amount of time to wait without seeing ECT(0)->CE is if there is an RFC3168 AQM, which you previously detected, and now might no longer be the bottleneck. under those conditions it would seem reasonable to be conservative about switching back.
> [BB] How and when did you "previously detect" an RFC3168 ECN AQM? I've read this para (and the whole thread) over and over, but I still can't work it out.
>
> [AB2] Most likely you are looking for something more clever than I intended to write. 'Previous detection' here just meant that in-band detection previously observed a packet it expected to be ECT(0) marked as CE, and thus assumes it has detected an RFC3168 ECN AQM - but sufficiently long ago that it is worth considering if that AQM is no-longer the bottleneck.

Understood. I (wrongly) took it to possibly imply that some other test 
had been running before your test.

Thanks for the other responses (snipped).


Bob

-- 
________________________________________________________________
Bob Briscoe                               http://bobbriscoe.net/

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