Re: [tsvwg] L4S DSCP (was: L4S drafts: Next Steps)

Kyle Rose <krose@krose.org> Wed, 24 March 2021 13:11 UTC

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From: Kyle Rose <krose@krose.org>
Date: Wed, 24 Mar 2021 09:11:38 -0400
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To: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
Cc: Pete Heist <pete@heistp.net>, "tsvwg@ietf.org" <tsvwg@ietf.org>
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Subject: Re: [tsvwg] L4S DSCP (was: L4S drafts: Next Steps)
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On Wed, Mar 24, 2021 at 8:46 AM Gorry Fairhurst <gorry@erg.abdn.ac.uk>
wrote:

> So injecting a little more history here.
>
> Some previous discussions are:
>
> The earliest discussion of L4S in the IETF that I recall was in 2015.
> When discussing, it was known that RFC4774 would allow experimentation
> with a diffserv domain (e.g., as in RFC 6660), but the practicalities of
> deploying an end-to-end Internet transport required an RFC to use a
> method that was not protected by a DSCP.


Understood. But I think the point that several folks have been making is
that an experimental RFC based solely on DSCP could have been published,
and opt-in experiments within and across guinea pig networks could have
begun, years ago. By now we'd have real world data about the behaviors of
L4S and TCP Prague that would likely have clarified many of the
long-running unknowns (e.g., regarding RTT sensitivity, behavior in the
presence of classic traffic, etc.) that are unlikely to be resolved by
simply thinking hard about the problem. Instead we've spun on a single
question, the allocation of an internet-wide code point to L4S, for several
years during which we could have been doing the work and gathering the data
required for understanding the likelihood of success in making that
allocation. Until we have real world data, those questions remain
unanswered and consensus cannot be achieved.

Kyle