Re: [tcpm] Early assignment of IANA TCP option number for AccECN

Michael Tuexen <michael.tuexen@lurchi.franken.de> Mon, 25 July 2022 14:04 UTC

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From: Michael Tuexen <michael.tuexen@lurchi.franken.de>
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Date: Mon, 25 Jul 2022 16:02:30 +0200
Cc: Mirja Kuehlewind <mirja.kuehlewind=40ericsson.com@dmarc.ietf.org>, Bob Briscoe <ietf@bobbriscoe.net>, tcpm IETF list <tcpm@ietf.org>
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To: "Scheffenegger, Richard" <rs.ietf@gmx.at>
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Subject: Re: [tcpm] Early assignment of IANA TCP option number for AccECN
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> On 25. Jul 2022, at 15:52, Scheffenegger, Richard <rs.ietf@gmx.at> wrote:
> 
> 
> Hi,
> 
> As one of the authors of the AccECN draft, which approaches the final
> stages, I wanted to see if there is support to ask IANA for an early
> assignment of the two TCP Option numbers for AccECN.
> 
> The background here is, that the current use of the experimental option
> in Linux (0xACC0 and 0xACC1) is not really documented - the draft only
> mentiones the experimental ID 0xACCE which was in use prior of the
> decision to go with two distinct option numbers.
If I understand the experimental options correctly, you could just use
kind=253, ExID=0xACCE
kind=254, ExID=0xACCE
to distinguish your two option using the assignment already made (for
example the kind=253 for Order 0, kind=254 for Order 1).
I don't see the ones used by Linux under
https://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-exids
> 
> However, the implementations between Linux and FreeBSD deviated - Linux
> using two different experimental IDs (see above), while the FreeBSD
> variant differentiated by an additional byte after the experiment ID
> (0xACCE).
I think the draft should describe how to use the experimental options.

Best regards
Michael (as an individual)
> 
> As some alignment here is needed in the code anyway, maybe this can make
> use of the  IANA assigned, final option numbers right away.
> 
> This showed up as one point during the Hackathon L3S interoperability
> testing.
> 
> If the group generally agrees, I would want to ask the chairs to support
> this request on behalf of the authors at IANA.
> 
> Also, I would like to suggest the assignment of 0xAC (172) and 0xAE
> (174) for use with the AccECN tcp option (ACcurate ecn, and Accurate
> Ecn) - but I admit that there is no other reason than vanity for these
> specific numbers.
> 
> Best regards,
>   Richard
> 
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