[Dart] draft-dart-dscp-rtp - way forward

"Black, David" <david.black@emc.com> Thu, 28 August 2014 18:12 UTC

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From: "Black, David" <david.black@emc.com>
To: "dart@ietf.org" <dart@ietf.org>
Date: Thu, 28 Aug 2014 14:12:05 -0400
Thread-Topic: draft-dart-dscp-rtp - way forward
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Cc: "Colin Perkins \(csp@csperkins.org\)" <csp@csperkins.org>
Subject: [Dart] draft-dart-dscp-rtp - way forward
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Looking at the list discussion, I think I see enough info to produce a
-05 version of this draft that should address all the last call items.

Reminder - we had 6 WG LC open issues and work items:

[A] Work item: Gorry Fairhurst's item (1), a new Section 5.4 on "single
PHB/DSCP for a single TCP connection, SCTP association or DCCP connection" -
I need to write this text, and will try to do that over the weekend.

--> Done, as noted previously, this text wound up in section 5.1 of the
--> -04 draft, along with slimming down of the corresponding guideline in
--> section 6.  I haven't seen a note from Gorry indicating that he's
--> checked it, though.

[B] Open issue: PHBs and DSCPs for RTCP.  The RTCP guideline bullet cannot
be revised until this open issue is resolved on the list.  See:
	http://www.ietf.org/mail-archive/web/dart/current/msg00156.html

--> I think I see rough agreement that for RTCP SRs, the same DSCP should
--> be used as the RTP stream being reported on, and for RTCP RRs, the 
--> DSCP to use should be the one that would be used to send a similar
--> RTP stream.

--> Beyond that, when an AF class is used, the DSCP with least likelihood
--> of drop should be used, and for a single RTCP report on multiple RTP
--> streams for which different DSCPs apply, it's up to the RTCP
--> implementation to choose one.

--> There's enough text to write here, including mentioning that RTCP
--> feedback is not currently used for congestion control, that I think
--> this should be in a new section 5.4, along with a rewritten guideline
--> item in Section 6.  I hope to send draft text later today.

[C] Work item:  Request to Ben Campbell for "additional text on context
(WebRTC, clue and bundle) for the Introduction and Abstract, plus for a
better example in Section 4."

--> Done, text is in -04, with some minor edits coming in -05.

[D] Open issue: Question to Harald Alvestrand - Does CNAME need to be used
in section 2.2 text?  I hope not.

--> Closed via a small text deletion in section 2.1 of -04 draft.

[E] Open issue: Harald Alvestrand's concerns about "differential treatment"
wrt Section 5.1 .  I don't completely understand these concerns, and suspect
that they may require an email discussion across the DART and RMCAT WGs
to sort through.

--> Deferred - Harald wanted to think about this, and I've seen nothing
--> further.  I'd suggest that IETF Last Call as an appropriate opportunity
--> to share any further thoughts, so I don't think there's anything to be done
--> about this now.

[F] Open issue: Harald Alvestrand's concerns about the RTCP multi-stream
optimization text in section 5.2 .  I don't think there's a problem here,
but I'm not an expert on the RTCP technology involved, and Harald may not
agree.  This is a different RTCP issue than [B].

--> Not an issue - At least Colin Perkins and I believe the existing
--> DART draft text is fine, so I don't think there's anything that needs
--> to be done for this.

I'm about to vanish for 2.5 weeks of vacation w/little to no email access,
so my goal is to get the -05 version submitted either tomorrow or Saturday.

Thanks,
--David
----------------------------------------------------
David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA  01748
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