The Conference Multiplexing and Management Centre

Where possible, the MICE partners and the Internet community are providing multimedia services by applications that multicast directly to all sites in the conference, with no centralised conference control or multiplexing centre. This is very desirable to achieve good scaling properties, but there are many reasons why many multi-point conferences will require a centralised Conference Management and Multiplexing Centre (CMMC). These reasons include:
  1. the mechanism for allowing communities to come in from different networks (e.g. EUROPANET, UK-US Pipe, EBONE and ISDN)
  2. a way to relay between different protocol and coding standards
  3. the incorporation of stations with reduced facilities (e.g. Basic Rate ISDN), video workstations without hardware Codecs, in higher quality and hence data rate conferences
  4. a centre for multiplexing video and voice
  5. a centre for conference reservation, resource control and management
  6. a centre for ensuring multicast of the shared workspace data, and possibly the voice, to all conferees
  7. a centre of expertise - remote users only need to know how to connect to the CMMC, and not how to interwork with (possibly incompatible) remote sites - the CMMC hides this extra functionality

The MICE philosophy is not that all video and audio streams should be forwarded through the CMMC, as this would negate many of the benefits of multicast and distributed conferencing applications. Only streams that actually require functional modification in the CMMC are routed directly through it.

The above figure shows a typical conference configuration. The three workstation simple multicast their video streams directly, and display the results in windows on the workstation screens. However, the three conference rooms using hardware codecs cannot display more than one stream at a time, and so require the multiplexing facilities of the CMMC. The CMMC also allows these conference rooms to interwork at greater frame rates and quality than the workstations can manage, whilst also remixing this video down to lower rates to be multicast to the workstation based sites. The CMMC also provides a bridge onto the ISDN network to allow sites without good internet connectivity to participate. Clearly any ISDN based conference has severe scaling limitations, but in this manner, a number of ISDN sites can be incorporated into conferences that do scale gracefully.

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