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This protocol defines extensions to [MS-CONFBAS] that enable SIP/Session Description Protocol (SDP)/RTP-based audio and video conference modalities and features within the multiple-MCU architecture that is described in [MS-CONFBAS].
The framework described in [MS-CONFBAS] calls for MCU entities to maintain separate, media type-specific communication sessions with each client. This protocol assumes that the communication protocol for signaling and media handshakes between clients and the logical AVMCU entity is the suite of protocols specified by the following:
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Protocol |
Description |
|---|---|
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Extensions to SIP |
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Extensions to SDP |
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An offer/answer Model with SDP |
This protocol defines the necessary interactions between the preceding protocols and the Centralized Conference Control Protocol (C3P), as described in [MS-CONFBAS]. For example, some of the interactions specified in this protocol are as follows:
Correlation of the C3P conference state and message element and attribute values with SIP URIs and SIP header values.
Correlation of the C3P conference state and message element and attribute values with the values of standard SDP attributes, as described in [RFC4566] and [RFC3264].
Processing of C3P commands that result in an action on one or more SIP dialogs between the server, or MCU, and the client or clients.
Changes in SIP dialog states between the MCU and the client that result in conference state changes and C3P notifications.
Logic rules based on C3P conference state that are factored into media-negotiation behavior whenever a client or MCU formulates an SDP offer or responds with an SDP answer.
This protocol does not specify any XML schema extensions beyond that of [MS-CONFBAS]. It does define semantics of some parts of the XML schema and C3P message constructs in more detail than those described in [MS-CONFBAS], particularly where [MS-CONFBAS] obsoletes, replaces, or deprecates parts of [RFC4575].
Therefore, this protocol does the following:
Defines semantics for the XML schema extensions to conference-medium-type that are described in [MS-CONFBAS].
Extends the semantics of conference-medium-type relative to [RFC4575].