[Standards-JIG] Media protocol LOI

Ulrich Staudinger us at die-horde.de
Wed Mar 10 09:32:08 UTC 2004


We need to merge
SIP: Session initiator protocol, used for signalling, non XML
SDP: Session descriptor protocol, used to describe a session, non XML
SDPng: same as SDP, just in XML syntax
RTP, RTSP, RTCP: realtime transfer protocol, used to send actual data, 
non XML
H323: signalling and session descriptor protocol, non XML

with
XMPP: IM protocol, in XML
MUC: XMPP's multi user conference protocol


Drawback 1:
A pure XML based approach should be favoured.

Drawback 2:
Existing SIP and H323 routers will not natively support the new, merged 
protocol.

Drawback 3:
The lack of a real rival to RTP/RTSP/RTCP speaks clearly for the use of 
RTP as media exchange protocol.

Drawback 4:
No existing media (both signalling and transfer) protocol reflects the 
MMUC use cases.

Sidenote 1:
The TINS jep merges SIP and SDPng already, but has some errors in the 
jep and  ignores MMUC.

Conclusion:
The merged specs will be a XMPP specific protocol definition covering 
the cases of call signaling, media exchange initiation and media multi 
user conference usage.


Proposed solution approach:

We use SDPng for session description.
The fundamental mechanics in SIP will be translated into SIP-XML, 
One-to-One media exchange is covered by this.
For MMUC we will simply *call* a relay, similar to dialing into a media 
conference.
All MMUC specific use cases [i.e. muting a user in a session, voicing on 
media level] will be covered within this same protocol.
MMUC will be closely related in structure to MUC.



Comments requested.




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