Re: [rtcweb] Open data channel issues

Michael Tuexen <Michael.Tuexen@lurchi.franken.de> Mon, 03 March 2014 14:41 UTC

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From: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [rtcweb] Open data channel issues
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On 26 Feb 2014, at 22:21, Christer Holmberg <christer.holmberg@ericsson.com> wrote:

> Hi,
> 
>>>> * Section 6.5
>>>> 
>>>> This section contains:
>>> 
>>>    Data channels can be opened by using internal or external
>>>    negotiation.  The details are out of scope of this document.
>>> 
>>>    A simple protocol for internal negotiation is specified in
>>>    [I-D.ietf-rtcweb-data-protocol] and MUST be supported.
>>> 
>>>> But internal and external negotiation are not defined in this document.
>>>> 
>>> 
>>>> I *thought* that internal negotiation was by definition negotiation 
>>> by use of  > rtcweb-data-protocol. 
>>> (draft-ejzak-mmusic-data-channel-sdpneg-00
>>> thinks so too,
>>>> but calls it "in-band negotiation".) There should be a good 
>>> definition of these  > terms, or reference to one. And more discussion 
>>> if there can be other kinds of  > internal negotiation. (If so, how 
>>> would one be chosen?)
>>> 
>>> Well, the text above says that ietf-rtcweb-data-protocol specifies an 
>>> internal negotiation protocol, so it's not that far off.  The split 
>>> does allow someone to use an alternative negotiation protocol 
>>> (internal or external).
>>> 
>>> How about:
>>> 
>>>    Data channels can be opened by using negotiation within the SCTP 
>>> association or external
>>>    negotiation.  External negotiation is defined as any method which 
>>> results in an agreement
>>>    as to the parameters of a channel and the creation thereof.
>>>    The details are out of scope of this document.
>>> 
>>>    A simple protocol for negotiation within the SCTP association is 
>>> specified in
>>>    [I-D.ietf-rtcweb-data-protocol] and MUST be supported.
>>> 
>>> Perhaps someone can wordsmith "external negotiation" better.
>> 
>> ISTM the issue is that Internal vs. External isn't the key distinction. 
>> What is key is that there is one method that MUST be *supported* but need not be the only one >used. Other mechanisms may be used. It doesn't really matter whether they are conducted >internally (over the SCTP association) or externally (anything else).
> 
> I think the MUST-be-supported-method is a separate question.
> 
>> E.g., I could use DCEP to establish one channel, and then use my own private protocol over that to >negotiate other channels. Would that be internal or external negotiation? Does it matter?
> 
> I guess they would both be in-band methods. Maybe using in-band and out-of-band terminology would be more clear - and more aligned with existing terminology.
OK, changed to in-band and out-of-band.

Best regards
Michael
> 
> Regards,
> 
> Christer
> 
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