[Standards-JIG] Media protocol LOI

tony.cheung at asiayeah.com tony.cheung at asiayeah.com
Wed Mar 10 10:00:00 UTC 2004

Some thoughts,

1. Instead of building an XML version of SIP, we actually only need an invitation or session establishment mechanism in XMPP. Building an xml version of sip may not be too useful because existing sip servers and clients cannot interoperate with the xml version anyway.

2. When we rebuild existing functionality as the current SIP infrastructure provides, we need to know our core values. Some ideas may be: simpler clients and servers, fewer interoperability issues, better firewall traversal or simply integration of existing XMPP infrastructure.

3. We may ignore H.323 for legacy reasons.

Tony Cheung

Ulrich Staudinger <us at die-horde.de> wrote:
>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
>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 
>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.
>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 
>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.
>Standards-JIG mailing list
>Standards-JIG at jabber.org

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