Subject: [rtcweb] Some final comments on draft-ietf-rtcweb-data-channel-11

From: Paul Kyzivat <[email-masked]>
Date: Mon, 11 Aug 2014 14:42:34 -0400

I just did another read-through of this draft, and identified a few 
things that I think need to be cleared up:

Association Usage:

draft-ietf-mmusic-sctp-sdp specifies new SDP notation for describing 
SCTP associations. It is not specific to rtcweb. For SCTP m-lines, it is 
necessary to name an "association-usage". Support for rtcweb data 
channels is one possible usage.

Currently draft-ietf-mmusic-sctp-sdp gives all of its examples using 
"webrtc-datachannel" as the association-usage. It does *not* currently 
define an IANA registry for association-usage, but it should. But it 
really is the wrong place to define this specific usage. Certainly 
draft-ietf-rtcweb-data-channel provides the *definition* of the usage. 
IMO it also ought to define and do the IANA registration of the name. 
(Obviously some coordination is required between this draft and the 
sctp-sdp draft, so that they are aligned on this.)

Also, can we PLEASE use a name that not specific to webrtc? This *will* 
be used in contexts where webrtc is not being used. (At least by CLUE.)

I propose that the name be "data-channel".

SCTP port:

*Something* needs to talk about SCTP ports. Currently they aren't 
mentioned either here or in JSEP. Since this document makes the point 
that this will be a user layer stack, and talks about the layering over 
DTLS, I think they ought to be mentioned here. They also probably need 
to be mentioned in JSEP, as part of aligning to the most recent version 
of draft-ietf-mmusic-sctp-sdp.

Only a little bit needs to be stated: that SCTP supports multiple SCTP 
ports, but that a particular SCTP association uses a single sctp port 
pair. (One port at each end of the SCTP association.) JSEP needs to 
specify how these ports are negotiated. (Via reference to 
draft-ietf-mmusic-sctp-sdp.)

Normative requirement for DCEP support:

While this draft references ietf-rtcweb-data-protocol normatively, and 
talks about it, I can find no explicit statement that implementations of 
this draft MUST also implement DCEP. AFAIK negotiation of the sctp 
association-usage defined by this draft in intended to mean that DCEP is 
also supported.

	Thanks,
	Paul

---

From: Michael Tuexen <[email-masked]>
Date: Tue, 26 Aug 2014 21:58:33 +0200

On 11 Aug 2014, at 20:42, Paul Kyzivat <[email-masked]> wrote:

> I just did another read-through of this draft, and identified a few things that I think need to be cleared up:
Hi Paul,

thank you very much for your comments. See my answers in-line.

Best regards
Michael
> 
> Association Usage:
> 
> draft-ietf-mmusic-sctp-sdp specifies new SDP notation for describing SCTP associations. It is not specific to rtcweb. For SCTP m-lines, it is necessary to name an "association-usage". Support for rtcweb data channels is one possible usage.
> 
> Currently draft-ietf-mmusic-sctp-sdp gives all of its examples using "webrtc-datachannel" as the association-usage. It does *not* currently define an IANA registry for association-usage, but it should. But it really is the wrong place to define this specific usage. Certainly draft-ietf-rtcweb-data-channel provides the *definition* of the usage. IMO it also ought to define and do the IANA registration of the name. (Obviously some coordination is required between this draft and the sctp-sdp draft, so that they are aligned on this.)
I really think that SDP related stuff should be in the MMUSIC ID including the IANA registrations.
> 
> Also, can we PLEASE use a name that not specific to webrtc? This *will* be used in contexts where webrtc is not being used. (At least by CLUE.)
> 
Anyone against it? I could change the name consistently in both RTCWEB IDs.
> 
> SCTP port:
> 
> *Something* needs to talk about SCTP ports. Currently they aren't mentioned either here or in JSEP. Since this document makes the point that this will be a user layer stack, and talks about the layering over DTLS, I think they ought to be mentioned here. They also probably need to be mentioned in JSEP, as part of aligning to the most recent version of draft-ietf-mmusic-sctp-sdp.
> 
> Only a little bit needs to be stated: that SCTP supports multiple SCTP ports, but that a particular SCTP association uses a single sctp port pair. (One port at each end of the SCTP association.) JSEP needs to specify how these ports are negotiated. (Via reference to draft-ietf-mmusic-sctp-sdp.)
What about adding
   SCTP uses the same port number concept as TCP and UDP do.  Therefore
   an SCTP association uses two port numbers, one at each SCTP end-
   point.
at the end of Section 5.
> While this draft references ietf-rtcweb-data-protocol normatively, and talks about it, I can find no explicit statement that implementations of this draft MUST also implement DCEP. AFAIK negotiation of the sctp association-usage defined by this draft in intended to mean that DCEP is also supported.
If I remember it correctly, the decision was to take such a statement out of the document...
Such a statement was in the second paragraph of
http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-07#section-6.5
and was taken out. See
http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-08#section-6.5
> 
> 	Thanks,
> 	Paul
> 
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