RFC 1453 (rfc1453) - Page 2 of 10

A Comment on Packet Video Remote Conferencing and the Transport/Network Layers

RFC 1453             Comments on Video Conferencing           April 1993


   for such an integrated control scheme.

2.  Remote Conferencing

   The challenges of remote conferencing is an application whose
   challenges may be met at the data link layer by the emerging
   broadband networks.  If so, important medical applications such as
   medical imaging for diagnosis and treatment planning would be
   possible [CHIM92].  Remote conferencing would permit imaging
   applications for life sciences through the use of national resource
   centers.  Collaboratory conferences in molecular modeling, design
   efforts, and visualization of data in numerous disciplines could
   become possible.

   At the Second Packet Video Workshop, held December, 1992, at MCNC in
   the Research Triangle Park, North Carolina, a recurrent theme was the
   use of multimedia in remote conferencing.  Its applications included
   the use of interactive, synchronized voice and video transmission,
   multicast transmission, data transfer, graphics transmission,
   noninteractive video and audio transmission, and data base query
   within a virtually shared workspace.  A few participants doubted the
   ability of current computer networks to handle these multimedia
   applications and preferred only connection-oriented, circuit-switched
   services.  Most participants, however, looked forward to using an
   integrated network approach.

2.1.  Remote Conferencing Functions and Requirements

   Remote conferencing as seen at the workshop requires a set of
   functions.  It must provide session scheduling that deals with
   initiating a session, joining in-progress sessions, leaving a session
   without tearing it down if there are multiple participants, and
   terminating a session.

   The remote-conferencing session needs a control subsystem that is
   either tightly controlled for an n-to-n connection for two to 15
   participants, or loosely controlled for a 1-to-n connection for any
   number of participants.  The Multipeer-Multicast Consortium is
   working on defining the control requirements and the mechanisms for
   control.  At the Packet Video Workshop, one participant presented a
   conference control protocol (CCP) shown in Figure 1 [CCP92].  In this
   architecture the CCP controls the Network Voice Protocol (NVP)
   [RFC 741] and the Packet Video Protocol (PVP) [PVP81] over the
   experimental Internet Stream Protocol, Version 2 (ST-II) [RFC 1190]
   rather than IP.

   Latency and intramedia synchronization and intermedia synchronization
   (lip-sync) are critical for the interactive voice and video streams



Chimiak