The protocol will provide negotiation for session membership, underlying communication topology and media configuration. In particular, the protocol will support a user initiating a multimedia multiparty session with other users (``calling'' other users) over the Internet by allowing a teleconferencing application on one workstation to explicitly rendezvous with teleconferencing applications running on remote workstations. Defining a standard protocol will enable session-level interoperability between different teleconferencing implementations.
The focus of the working group is to design a session agreement protocol that supports tightly-controlled conferences in addition to the loosely-controlled ones currently carried on the MBone. Loosely-controlled sessions have little to no interaction among members, thus limiting their ability to provide security or coordination of session attributes (e.g., quality-of-service options for time-critical media, floor control for media flows). Users may learn of loosely-controlled sessions using the ``sd'' utility or other out of band mechanisms (e.g., e-mail, WWW). However, there is clearly also a need for more tightly-controlled sessions that provide mechanisms for directly contacting other users to initiate a conference and for negotiating conference parameters such as membership, media encodings and encryption keys. In addition, these sessions should support renegotiation during a session, for example, to add or delete members or change the media encoding.
The main goal of the working group will be to specify the session control protocol for use within teleconferencing software over the Internet. The working group will focus on the aspects of the session control problem that are well understood, while keeping an eye on evolving research issues. Toward this end, the working group has made an inventory of existing conferencing systems and their session control protocols. The working group will document the requirements of the existing prototypes as a basis for the protocol development. The working group will iteratively refine the protocol based on implementation and operational experience.
Furthermore, the working group will coordinate with other efforts related to multimedia conferencing, such as directory services for cataloging users and conferences, the RTP and RTCP protocols developed by the Audio/Video Transport Working Group, resource reservation and management at the network level, and schemes for multicast address allocation.