Re: [tsvwg] [Ecn-sane] Comments on L4S drafts

Jonathan Morton <chromatix99@gmail.com> Thu, 04 July 2019 12:24 UTC

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From: Jonathan Morton <chromatix99@gmail.com>
In-Reply-To: <ce4b1e2d-3bc8-265c-6bcd-5a26b4dd89e9@bobbriscoe.net>
Date: Thu, 4 Jul 2019 15:24:18 +0300
Cc: Luca Muscariello <muscariello@ieee.org>, "Holland, Jake" <jholland@akamai.com>, "ecn-sane@lists.bufferbloat.net" <ecn-sane@lists.bufferbloat.net>, "tsvwg@ietf.org" <tsvwg@ietf.org>
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References: <364514D5-07F2-4388-A2CD-35ED1AE38405@akamai.com> <cc446538-cf23-4fd0-12df-7839ec6c04a2@bobbriscoe.net> <CAH8sseSPz3FoLWZNPEJcwb4xQNYk_FXb8VS5ec9oYwocHAHCBg@mail.gmail.com> <4aff6353-eb0d-b0b8-942d-9c92753f074e@bobbriscoe.net> <D13294C4-105C-4F58-A762-6911A21A18C6@akamai.com> <CAH8sseSQaCbknok--hf=DgwzCs3OnnkKjPy5bdLgnzjq7-+c_w@mail.gmail.com> <ce4b1e2d-3bc8-265c-6bcd-5a26b4dd89e9@bobbriscoe.net>
To: Bob Briscoe <ietf@bobbriscoe.net>
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Subject: Re: [tsvwg] [Ecn-sane] Comments on L4S drafts
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> On 4 Jul, 2019, at 2:54 pm, Bob Briscoe <ietf@bobbriscoe.net> wrote:
> 
> The phrase "relative to a FIFO" is important. In a FIFO, it is of course possible for flows to take more throughput than others. We see that as a feature of the Internet not a bug. But we accept that some might disagree...

Chalk me up as among those who consider "no worse than a FIFO" to not be very reassuring.  As is well documented and even admitted in L4S drafts, L4S flows tend to squash "classic" flows in a FIFO.

So the difficulty here is twofold:

1: DualQ or FQ is needed to make L4S coexist with existing traffic, and

2: DualQ can be defeated by an adversary, destroying its ability to isolate L4S traffic.

I'll read your reply to Jake when it arrives.

 - Jonathan Morton