Re: [MMUSIC] BUNDLE and DATA CHANNEL - Paul's example

Paul Kyzivat <pkyzivat@alum.mit.edu> Mon, 29 April 2013 19:41 UTC

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Date: Mon, 29 Apr 2013 15:41:51 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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To: Martin Thomson <martin.thomson@gmail.com>
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Cc: "mmusic@ietf.org" <mmusic@ietf.org>, Christer Holmberg <christer.holmberg@ericsson.com>
Subject: Re: [MMUSIC] BUNDLE and DATA CHANNEL - Paul's example
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One more thing - a question for all:

Do you agree that there is a need to support more than one way to demux 
RTP, and hence a need to signal what way is to be used?

Or do you think we will be able to reach agreement on a single 
algorithm, so that signaling of the algorithm isn't required?

	Thanks,
	Paul	

On 4/29/13 2:13 PM, Martin Thomson wrote:
> On 29 April 2013 10:05, Paul Kyzivat <pkyzivat@alum.mit.edu> wrote:
>> On 4/29/13 10:41 AM, Christer Holmberg wrote:
>>> In your example there is only one SCTP m- line, and in WebRTC I guess it
>>> will also be the case, but SDP doesn't prevent you from using multiple SCTP
>>> m- lines - unless BUNDLE explicitly forbids it, that is.
>>
>> I agree. If we want to support that, then the obvious way (for DTLS/SCTP) is
>> via SCTP port. That depends on there being a way to specify the SCTP with
>> DTLS/SCTP. That has come and gone from the SDP proposal for SCTP.
>
> I don't care whether SDP supports it or not, I care whether it makes
> sense to do it at all.
>
> There's a reason why you might not want to mux SCTP - it's a protocol
> with multiplexing support.  Multiplexing outside of it is at best a
> crude thing to do and at worst a way to dilute congestion signals.
>
> I can understand how you can conceive of scenarios where different
> application layer protocols don't play well together enough that you
> want more aggressive separation.  I don't see significant value in
> supporting those scenarios.
>
> That doesn't completely preclude the future use of SCTP port for
> demux, but it does constrain complexity.
>