Re: [tcpm] [tsvwg] New Version Notification for draft-grimes-tcpm-tcpsce-00.txt

"Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net> Sat, 02 November 2019 23:26 UTC

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From: "Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net>
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To: "alex.burr@ealdwulf.org.uk" <alex.burr@ealdwulf.org.uk>
Date: Sat, 02 Nov 2019 16:26:18 -0700
CC: Jonathan Morton <chromatix99@gmail.com>, "\"Rodney W. Grimes\"" <freebsd@gndrsh.dnsmgr.net>, "\"tcpm@ietf.org\"" <tcpm@ietf.org>, "\"tsvwg@ietf.org\"" <tsvwg@ietf.org>
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Subject: Re: [tcpm] [tsvwg] New Version Notification for draft-grimes-tcpm-tcpsce-00.txt
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Rod Grimes                                                 rgrimes@freebsd.org
Alex,
With respect to draft-ietf-tcpm-accurate-ecn and
draft-grimes-tcpm-tcpsce compatibility:
  When accurate ecn (AccECN) fails to negotiate an AccECN capable session
  it falls back to RFC3168 conformance, leaving a state that is fully
  compatible with SCE, hence they are compatible.

  I am currently working on a revision to draft-grimes-tcpm-tcpsce and
  hopefully can cover this "compatible" situation in the draft itself.

With respect to "There are no IANA considerations":
  You are correct, reworking that in several respects, hope to remove
  references to the NS bit for most parts and simply state that this
  draft for "IANA considerations" is requesting a bit, with the former
  NS bit prefered.

Regards,
Rod

>  Rod, Jonathan,
> ?I could be wrong, but it appears to me that this draft does not merely not make use of draft-ietf-tcpm-accurate-ecn,it's incompatible with it. Is this the case? Of course SCE is a competitor to L4S, but the accurate-ecn draft also asserts that there are other uses for accurate-ecn besides L4S (DCTCP and ConEx) . It would be useful if you (the TCPSCE authors ) could state your position on those other uses, for the record. 
> 
> Also, presumably it is incorrect that "There are no IANA considerations", since IANA would need to change the NS bit.
> 
> Regards,
> Alex
> 
> Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> wrote:
> > > Rod,
> > > 
> > > This draft appears to be focused on obtaining a TCP header bit for SCE.
> > 
> > Yes, that is correct.
> > 
> > > As an alternative to this single-bit proposal, please take a look at draft-ietf-tcpm-accurate-ecn (https://datatracker.ietf.org/doc/draft-ietf-tcpm-accurate-ecn/) and consider how that functionality might (or might not) be usable with SCE. 
> > 
> > I specifically did not do what Accurate Ecn attempts as that requires
> > a TCP option negotiation at connection establishment to negotiate the
> > overloading of other TCP header bits.? SCE only needs 1 new bit, and
> > does not alter the behavior of any current bits.
> > 
> > This proposal (TCPSCE) does not in any way effect the current use of
> > any of the other bits, and use of the NS bit should be fully backwards
> > compatible and ignored by pre SCE implementations and does not require
> > a TCP option negotiation.
> > 
> > I have to get additional data but have been lead to understand that
> > adding a tcp option and doing that negotiation is going to cause a
> > great deal of pain in the ability to deploy accurate ecn as it is
> > currently designed due to middle box inspection and handling.
> > 
> > Regards,
> > Rod
> > 
> > > Thanks, --David
> > > 
> 
> 
> 
> 

-- 
Rod Grimes                                                 rgrimes@freebsd.org