Subject: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-sctp-sdp-04.txt

From: Paul Kyzivat <[email-masked]>
Date: Tue, 02 Jul 2013 11:00:53 -0400

On 6/30/13 12:34 PM, Salvatore Loreto wrote:
> Hi there,
>
> I have produced a new version to address all the comments received on
> the mailing list
>
> Comments, feedback and questions are very well appreciated and requested
>
> cheers
> Salvatore

Here are some things that I found. I'm pretty sure some of them have 
been discussed on the list before.

In section 5.1:

    The sctpmap attribute maps from a port number (as used in an "m="
    line) to an encoding name denoting the payload format to be used on
    top of the SCTP association or the actual protocol running on top of
    it.

While the earlier examples may clarify, this text isn't clear about what 
"port" means. The m-line contains a <port> field, and a <fmt> field that 
has been said to contain an sctp-port. I think this text should 
reference the <fmt> field:

    The sctpmap attribute maps from a <fmt> number (as used in an "m="
    line) to an encoding name denoting the payload format to be used on
    top of the SCTP association or the actual protocol running on top of
    it.

Also in this section you define <protocol> as <labelstring>. There is no 
specification of how/where such things are defined - e.g. a registry. 
That can't be.

In the case of rtpmap, the <media> field from the m-line, plus the 
<encoding-name> from the rtpmap-line form a mime-type that is registered 
in IANA. Some of the examples suggest that the same approach is intended 
for sctpmap. But this needs to be clearly specified. If you don't intend 
to follow this approach, then for the examples (such as T38) to be valid 
there will need to be definitions of them is whatever registration 
scheme you propose.

Section 9.3:

The example shows a=webrtc-DataChannel lines.

Are these defined in any rfc or draft? I can't find one. I think you 
should either use real examples, that are defined somewhere, or else 
make clear that you are using a hypothetical example.

	Thanks,
	Paul