Editor's Note: The CONFCTRL BOF became the MMUSIC WG on 6/24/93. CURRENT_MEETING_REPORT_ Reported by Eve Schooler/ISI and Dean Blackketter/Apple Minutes of the Conferencing Control BOF (CONFCTRL) One task of the initial BOF sessions was actually to find a suitable definition for ``conference control'', since the topic has been bandied about for some time in the Remote Conferencing BOF and the Audio/Video Transport Working Group. By broadly defining multimedia conferencing as collaborations in two dimensions (members and media), we defined conference control as the management and coordination of (multiple) conference members in (multiple) media. How does conference control pertain to the ongoing RemConf efforts for an overall remote conferencing architecture, and in particular to the developments in the AVT Working Group of a real-time transport protocol? We agreed that there is a need for a session layer control protocol to perform higher layer functions than the protocol proposed in the AVT Working Group. For example, three aspects of conference control might include session, connection and configuration management; session management entails who is involved in a conference, connection management involves the topology of who is seeing whom in each media, and configuration management is the negotiation of differences in end-system capabilities. We identified the beginnings of some design criteria for this protocol. First, it should be kept simple, yet extensible. We would like for it to accommodate a range of session styles -- beyond the unmoderated sessions already available through vat, dvc, nv et al. We also recognized the need to separate short-term from long-term functionality goals. We brainstormed about which functions MUST be supported versus which we would like to have supported. It falls out of our definition for conference control that, at minimum, support is needed for both membership and media control. Membership control might include admission policies (such as user identification, user payment, meeting sponsorship), whereas media control might encompass capability descriptions, synchronization policies, and floor control (media focus). In both dimensions, session setup, maintenance and/or modification must be supported. Other features deemed important but probably of lower priority included security (in the form of authentication and encryption), as well as feedback channels for bandwidth balancing. We also listed outside services to which we expect a conference control protocol to interface: a suite of directory services for cataloguing users, conferences, and shared devices; bandwidth allocation and reservation mechanisms; and a scheme for multicast address allocation. Our assumption is that eventually these outside services will be available. To understand the range of capabilities to support in a conference 1 control protocol, we explored the types of sessions that might arise. Our wishlist included a continuum of session scenarios (although the picture below only lists a sample from the full range and only crudely approximates an ordering). ``Secure'' variations on these meetings were also discussed. impromptu hallway meetings classroom seminar pay-per-view |-------|-------|--------|-------|-------|-------|-------|-------| pt2pt arch design panel lecture TV phone review/ discussion/ broadcast call ``quilting bee'' presidential debate Observations made about the spectrum were that there are different types of participation (active and passive), that there are gradations of identification policies (known vs anonymous participants), that there may be extreme variations in the degree of interconnectivity among participants, etc. We discussed that for simplicity's (and implementation's) sake, we are likely to need to select a small number of session types that the protocol should support. A rough breakdown into four general session models was presented: 1. Point-to-point calls. 2. Small, tightly-controlled sessions: N-way interconnectivity. 3. Medium-sized, loosely-controlled sessions: lighter-weight model. 4. Very large, fixed sessions: unidirectional broadcasts. There was discussion that other standards bodies (CCITT) have explored issues in some aspects of connection control (for B-ISDN). In addition, existing prototype conferencing tools should be examined for leads on tradeoffs regarding conference management. Attendees Dean Blackketter deanb@apple.com Wo Chang wchang@nist.gov Osmund de Souza osmund.desouza@att.com Hans Eriksson hans@sics.se Don Hoffman don.hoffman@eng.sun.com Oliver Jones oj@pictel.com Jim Knowles jknowles@binky.arc.nasa.gov Bill Manning bmanning@sesqui.net 2 Kathleen Nichols nichols@apple.com Jim Perchik perchik@athena.mit.edu Eve Schooler schooler@isi.edu Henning Schulzrinne hgs@research.att.com Scott Stein scotts@apple.com Thierry Turletti turletti@sophia.inria.fr Abel Weinrib abel@bellcore.com 3