Re: [MMUSIC] SDPNEG: How to disable DCEP

"Roni Even (A)" <roni.even@huawei.com> Sun, 28 April 2019 06:21 UTC

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From: "Roni Even (A)" <roni.even@huawei.com>
To: Paul Kyzivat <pkyzivat@alum.mit.edu>, Christer Holmberg <christer.holmberg@ericsson.com>, "mmusic@ietf.org" <mmusic@ietf.org>
Thread-Topic: [MMUSIC] SDPNEG: How to disable DCEP
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Date: Sun, 28 Apr 2019 06:21:41 +0000
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References: <8A9AAAC7-FB2D-4884-BAC6-268B98C7A0F0@ericsson.com> <eba7d468-a2a3-8c5f-c2b0-fa515fb2e55c@alum.mit.edu> <81169C37-95F2-418A-A221-CCC623392CD2@ericsson.com> <563cf2bd-474a-8fef-ceaf-e2c72ebc6dc4@alum.mit.edu>
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Subject: Re: [MMUSIC] SDPNEG: How to disable DCEP
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Hi,
I think that sections 6.3 and 6.4 that discuss offer/answer say that dcmap is the indication of ruing non dcep.
The example in section 7 say that if dcmap is rejected dcep may be negotiated.
Maybe this line form section 7 should be in section 6.4?

Roni

-----Original Message-----
From: mmusic [mailto:mmusic-bounces@ietf.org] On Behalf Of Paul Kyzivat
Sent: Friday, April 26, 2019 6:16 PM
To: Christer Holmberg; mmusic@ietf.org
Subject: Re: [MMUSIC] SDPNEG: How to disable DCEP

On 4/26/19 5:37 AM, Christer Holmberg wrote:
> Hi Paul,
> 
> So, what is your suggestion? __

It looks to me like the 2nd paragraph of Appendix A is the right place for this:

    A WebRTC application creates a data channel by providing a number of
    setup parameters (subprotocol, label, maximal number of
    retransmissions, maximal retransmission time, order of delivery,
    priority).  The application also specifies if it wants to make use of
    the negotiation using the DCEP [I-D.ietf-rtcweb-data-protocol], or if
    the application intends to negotiate data channels using the SDP
    offer/answer protocol.

I'm inclined to tweak the above as follows:

    ...
    the application intends to negotiate data channels using the SDP
    offer/answer protocol, or both.

And then, the note at the end of the section can be augmented:

    Note: The above SDP media description does not contain any channel-
    specific information. If data channels are to be negotiated using
    SDP, then the above will be supplemented as specified in Sections
    6.3 and 6.4.

But I'm not sure about "The application also specifies...". Is this referring to something specific in the webrtc API? If so, does it permit both? The presence of dcmap in the SDP will indicate the intent to use SDP negotiation, but must this first be enabled in the API?

	Thanks,
	Paul

> Regards,
> 
> Christer
> 
> On 25/04/2019, 1.25, "mmusic on behalf of Paul Kyzivat" <mmusic-bounces@ietf.org on behalf of pkyzivat@alum.mit.edu> wrote:
> 
>      The distribution of specs across multiple documents makes it really
>      fuzzy what is normative for what.
>      
>      Perhaps something should be said about the validity of using a
>      webrtc-datachannel media stream for establishing data channels via SDP
>      with dcmap and/or DCEP. I don't think this is said anywhere else.

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