Subject: [MMUSIC] IANA considerations for draft-ietf-mmusic-sctp-sdp

From: Paul Kyzivat <[email-masked]>
Date: Fri, 25 Jul 2014 19:26:10 -0400

There are some loose ends to tie up with IANA for this draft to be complete:

This draft defines new proto values:

SCTP
SCTP/DTLS
DTLS/SCTP

They need to be registered in the IANA SDP Parameters registry Proto table.

And then, SDP (RFC4566) says:

       For media using other transport protocols, the <fmt> field is
       protocol specific.  Rules for interpretation of the <fmt> sub-
       field MUST be defined when registering new protocols (see Section
       8.2.2).

This draft needs to define protocol specific rules for <fmt> when used 
with the new family of SCTP protos.

For the moment, I think the rules should probably be that there must be 
exactly one <fmt> value on the m-line with these protos. For what values 
are valid, I think we need a new IANA registry. It should be a new table 
within SDP Parameters, and should probably look something like this:

Name: media/fmt values for SCTP family protos

Media         Fmt            Reference
-----------   ------------   ----------
application   raw-sctp       [some SCTP rfc]
application   data-channel   [draft-ietf-rtcweb-data-channel]

Note that I'm suggesting registering media/fmt pairs. If we don't, then 
there is no specification of what the significance of <media> is with 
these protos. The alternative would be to specify that only 
"application" can be used. But registering pairs makes more sense to me. 
(Somebody may come up with an audio or video application-usage that 
makes sense.)

(We *could* register these formats on a per-proto basis, rather than for 
the whole family of sctp protos. I see no compelling reason to do that, 
and good reasons not to.)

This draft needs to establish the registry, and populate the value for 
raw SCTP. I *think* the reference for the semantics of raw-sctp can be 
just a reference to a basic SCTP rfc. Or maybe we need to reference 
*this* draft and include a paragraph explaining what raw access to an 
SCTP association means.

Ideally draft-ietf-rtcweb-data-channel would register the data channel 
fmt, since it defines how it works. If need be, *this* draft could 
register it.

And note that I'm suggesting calling the fmt "data-channel" rather than 
"webrtc-datachannel", because it can, and will, be used in contexts 
where webrtc is not in use.

	Thanks,
	Paul