Re: [MMUSIC] New draft version draft-ietf-mmusic-data-channel-sdpneg-03

Juergen Stoetzer-Bradler <> Wed, 22 July 2015 12:08 UTC

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From: Juergen Stoetzer-Bradler <>
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Date: Wed, 22 Jul 2015 14:08:08 +0200
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Subject: Re: [MMUSIC] New draft version draft-ietf-mmusic-data-channel-sdpneg-03
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Hi Paul,

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

Thank you,

On 21.07.2015 21:03, Paul Kyzivat wrote:
> Thanks for doing this work. The draft is shaping up. Comments below.
> On 7/21/15 9:13 AM, Juergen Stoetzer-Bradler wrote:
>> Have submitted version 03 of draft-ietf-mmusic-data-channel-sdpneg.
>> This version solves Roni's comments 1 and 2 and 5 to 9
>> (,
>> Roni's 10th comment was about the still missing IANA registration text
>> for the new SDP attributes dcmap and dcsa. Have added related
>> section headers, but the actual text still needs to be added.
>> Roni's comments 3 and 4 were related to the (JaveScript) API related
>> text parts.
>> Have removed most of these text parts.
>> However, section 5.2.2 still contains some API related text.
>> Before also removing this I'd like to raise a slightly broader question.
>> Sections 5.1 and 5.2 contain informative generic non-DCEP negotiation
>> related text,
>> which could mostly be removed from the document, as this draft now
>> exclusively
>> focuses on SDP offer/answer extensions.
>> Some parts might be moved to the related SDP offer/answer specific text
>> in section 6.
>> Have added a couple of related editor note's to sections 5.1 and 5.2
>> indicating
>> which text parts I think could be completely removed and which could be
>> moved to
>> section 6.
>> Would that be agreeable?
> I think the concept makes sense. Right now it is extremely hard to read the draft with all the 
> editors notes and figure out how it might flow with those changes. IMO it would be better for you 
> to go ahead and make the changes, so that the result can be reviewed to see how it works.

[Juergen] Ok. Will do that.

> I find all the discussion of "non-DCEP negotiation" awkward. I do think it is better to simply 
> discuss "SDP negotiation". I don't think we need treatise on how other negotiations, other than 
> DCEP or SDP, work.

[Juergen] Ok. Had a look again at the text parts, where "non-DCEP negotiation" is mentioned. I think 
most of the related sentences could anyhow be deleted as discussed above.

> Other misc comments:
> Section 6 says:
>    This SDP extension can only be used with the SDP offer/answer model.
> I'm not sure if that is true or not. I think it would be better to say:
>    This SDP extension only defines usage in the context of SDP
>    offer/answer.

[Juergen] Agree. This is the intended meaning. Will change the sentence as you propose.

> Section 6.1.1 says:
>    The intention of exchanging these attributes is to create data
>    channels on both the peers with the same set of attributes without
>    actually using the DCEP [I-D.ietf-rtcweb-data-protocol].
> I think there is a bit more to say about this. I suggest:
>    The intention in exchanging these attributes is to create, on two
>    peers, without use of DCEP [I-D.ietf-rtcweb-data-protocol], matched
>    pairs of oppositely directed data channels having the same set of
>    attributes.

[Juergen] Agree. Will changes this.

> Section says:
>    The 'max-retr' parameter indicates the maximal number a user message
>    will be retransmitted.
> In the edit a bit was lost. This should say:
>    The 'max-retr' parameter indicates the maximal number of times a
>    user message will be retransmitted.

[Juergen] Indeed. Thanks.

> Section 6.2.1 says:
>    However, an SDP offer/answer exchange MUST NOT be
>    initiated if the associated SCTP stream is already negotiated via
>    DCEP.
> This phrasing is awkward and confusing. I suggest:
>    However, an SCTP stream MUST NOT be referenced in a dcmap or
>    dcsa attribute of an SDP offer/answer exchange if the associated
>    SCTP stream has already been negotiated via DCEP.

[Juergen] That's more precise. Thanks much. Will change the sentence as you suggest.

> Note: above comments based only on reviewing the diffs. I didn't do another full review of the 
> document.
>     Thanks,
>     Paul