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looSely-couPLed sIp deviCES

Document Charter looSely-couPLed sIp deviCES WG (splices)
Title looSely-couPLed sIp deviCES
Last updated 2012-01-25
State Approved
WG State Concluded
IESG Responsible AD Gonzalo Camarillo
Charter edit AD (None)
Send notices to (None)


Disaggregated media refers to the ability for a user to create a
multimedia session combining different media streams coming from
different devices under his or her control so that they are treated by
the far end of the session as a single media session.

Generally, a given participant uses a single device to establish (or
participate in) a given multimedia session. Consequently, the SIP
signaling to manage the multimedia session and the actual media
streams are typically co-located in the same device. In scenarios
involving disaggregated media, a user wants to establish a single
multimedia session combining different media streams coming from
different devices under his or her control. This creates a need to
coordinate the exchange of the those media streams within the
multimedia session.

There are a number of existing mechanisms that can be used to
coordinate different devices under user's control and to involve them
in the call (e.g. Message Bus (Mbus) [RFC3259], Megaco [ITU-T H.248.1]
and SIP 3pcc [RFC3725]). However, these mechanisms are intended to be
used in "tightly coupled" scenarios. The use of all those mechanisms
requires the presence of a "master" device. That is, at least one
among the different devices under the control of the same user must
support the control mechanism and be able to become a controller for
the other devices in the call. Moreover, the "master" device is
supposed to remain involved in the user's session for its entire
duration given that performing a handover of the master role is
typically cumbersome and sometimes impossible.

The objective of this working group is to develop a framework for
disaggregated media in "loosely-coupled" scenarios, where no single
device needs to remain in the session for its entire duration and no
single device needs to act as a master. Coordination among devices in
this type of scenario is less tight than in the scenarios described
above since they do not assume central elements with complete
knowledge of the whole media session. While the framework may describe
how to use existing mechanisms (e.g., the SIP REFER method) to
coordinate devices, the working group will not develop new device
coordination mechanisms. The framework may identify the need for new
(non-device-coordination) mechanisms to enable the implementation of
loosely-coupled scenarios. In case the need for such new mechanisms is
identified, the working group will specify them.

Specifically, the proposed working group will develop the following

  1. A framework document describing key considerations for the exchange
    of disaggregated media in SIP. The document will include use cases
    and examples. The document may indentify the need for new
    mechanisms or extensions to existing mechanisms.

  2. Specifications of new mechanisms or extensions to existing
    mechanisms if the need is identified in the framework.