Re: [MMUSIC] draft-ietf-mmusic-sctp-sdp-07 SCTP SDP syntax question

Christian Groves <> Wed, 01 October 2014 23:24 UTC

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Subject: Re: [MMUSIC] draft-ietf-mmusic-sctp-sdp-07 SCTP SDP syntax question
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On 2/10/2014 12:20 AM, Paul Kyzivat wrote:
> On 10/1/14 3:29 AM, Salvatore Loreto wrote:
>>>> 7) Cl.10: How will this registry relate to the “WebSocket 
>>>> Subprotocol Name Registry” 
>>>> (
>> <Sal>
>> It is not related. The 'association-usage' specifies how the SCTP 
>> association will be used.
>> For example in the case of webrtc-datachannel value it would indicate 
>> how to pair certain streams,
>> how to consider specific stream etc.
>> as described in 
>> and in
>> the WebSocket Subprotocol Name Registry is used to populate the 
>> protocol field in the
>> protocol field in 
> I agree.
> The association-usage is describing how the association as a whole, 
> including all of the streams, is used/managed.
> It doesn't provide a means to separately describe how individual 
> streams within it are to be used. If that is to be done in SDP then 
> something like draft-ejzak... would be required.

[CNG] My comments on this are in the context of the note in cl.10 of the 
draft: "[Note] TBD whether a new registry is necessary to register the 
different possible "association-usage" values."

I'm just thinking of the specification effort to introduce new 
sub-protocols. Consider a gateway scenario where I have a DTLS/SCTP 
association running datachannel with bfcp and on the other side a SCTP 
association running BFCP. In either scenario bfcp runs in an SCTP 
stream. However it means to introduce BFCP (and any other protocol) we 
have to update two registries with essentially the same value.

If we do have a new registry just for "association-usage" it would be 
good to have some text with regards to a template of information that 
someone registering the information would need to consider. i.e. what 
information would someone need to specify to registry BFCP as opposed to 
just registering BFCP as websocket sub-protocol.

Regards, Christian

>     Thanks,
>     Paul
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