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

Pete Heist <> Fri, 26 July 2019 13:10 UTC

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From: Pete Heist <>
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Date: Fri, 26 Jul 2019 09:10:46 -0400
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To: "De Schepper, Koen (Nokia - BE/Antwerp)" <>
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Subject: Re: [tsvwg] [Ecn-sane] Comments on L4S drafts
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> On Jul 25, 2019, at 12:14 PM, De Schepper, Koen (Nokia - BE/Antwerp) <> wrote:
> We have the testbed running our reference kernel version 3.19 with the drop patch. Let me know if you want to see the difference in behavior between the “good” DCTCP and the “deteriorated” DCTCP in the latest kernels too. There were several issues introduced which made DCTCP both more aggressive, and currently less aggressive. It calls for better regression tests (for Prague at least) to make sure it’s behavior is not changed too drastically by new updates. If enough people are interested, we can organize a session in one of the available rooms.
> Pete, Jonathan,
> Also for testing further your tests, let me know when you are available.

Regarding testing, we now have a five node setup in our test environment running a mixture of tcp-prague and dualq kernels to cover the scenarios Jon outlined earlier. With what little time we’ve had for it this week, we’ve only done some basic tests, and seem to be seeing behavior similar to what we saw at the hackathon, but we can discuss specific results following IETF 105.

Our intention is to coordinate a public effort to create reproducible test scenarios for L4S using flent. Details to follow post-conference. We do feel it’s important that all of our Linux testing be on modern 5.1+ kernels, as the 3.19 series was end of life as of May 2015 (, so we'll try to keep up to date with any patches you might have for the newer kernels.

Overall, I think we’ve improved the cooperation between the teams this week (from zero to a little bit :), which should hopefully help move both projects along...