Re: [MMUSIC] New Version Notification for draft-ietf-mmusic-data-channel-sdpneg-05.txt

Juergen Stoetzer-Bradler <> Tue, 06 October 2015 15:19 UTC

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From: Juergen Stoetzer-Bradler <>
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Date: Tue, 06 Oct 2015 17:18:29 +0200
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Subject: Re: [MMUSIC] New Version Notification for draft-ietf-mmusic-data-channel-sdpneg-05.txt
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Hello Paul,

Thanks much for your comments.
Please see my replies inserted below.

Thank you,

On 05.10.2015 23:12, Paul Kyzivat wrote:
> These changes mostly seem good. I have a couple of small points:
> * Section
> This section starts with:
>    The multiplexing category of the "a=dcmap:" attribute is SPECIAL.
>    Usage of this attribute is only applicable when associated with
>    UDP/DTLS/SCTP or TCP/DTLS/SCTP proto SDP "m" lines.
> One issue is that usage of this attribute is also defined over pure SCTP. So I think it would be 
> more accurate to say "*Multiplexing* of this attribute...".
[Juergen] In this second paragraph of I wanted to express that this document defines the 
a=dcmap attribute only for
X/DTLS/SCTP attribute lines - quite similar to the mux category description of the a=sctp-port 
attribute in section 5.3 of draft-ietf-mmusic-sctp-sdp-15.
As multiplexing of multiple SCTP associations over one DTLS connection is not considered by 
and as there can be just one DTLS connection within one BUNDLE group (potentially used by multiple 
media descriptions within this BUNDLE group)
my understanding is that in fact there can be just one SCTP association over DTLS within such a 
BUNDLE group.
Therefore I thought there's no need to define a multiplexing semantic for the a=dcmap (and a=dcsa) 
attribute (as described in the 3rd paragraph).

I am not sure "Multiplexing of this attribute is only applicable when associated with X/DTLS/SCTP 
"m" line" would be consistent
with the intended meaning of the 3rd paragraph.

> Also, saying this is *only applicable* unnecessarily blocks future changes. I think it would be 
> better to say *only defined*, or *outside the scope*.
[Juergen] Agree. How about the following?
"This document defines usage of this attribute only when associated with UDP/DTLS/SCTP or 
TCP/DTLS/SCTP proto SDP "m" lines".

> * Section
> Analogous comment to that for
> * Section 8.2:
> IIUC current practice is for documents coming through WGs to list the WG chair (e.g. 
> as the contact.
[Juergen] I see, thanks,
Thus contact name would then e.g. be "MMUSIC Chairs"?

>     Thanks,
>     Paul
> On 10/5/15 8:56 AM, Juergen Stoetzer-Bradler wrote:
>> Hello,
>> This version 05 adds the IANA registration sections for the dcmap and
>> dcsa attributes
>> and adds new mux category related sections for both attributes.
>> It also adds [I-D.ietf-mmusic-sdp-mux-attributes] to the list of
>> normative references,
>> as that draft is referenced by the two new mux category sections.
>> Additionally, this version updates section regarding the dmap's
>> 'subprotocol' parameter
>> as per the related MMUSIC discussion initiated by Christian in August,
>> Thanks,
>> Juergen