Efficient Group Communication
               with Guaranteed Quality of Service




             Clemens Szyperski and Giorgio  Ventre

                        The Tenet Group
            International Computer Science Institute
                              and
                   Computer Science Division
                       Department of EECS
               University of California, Berkeley

          e-mail: {szyperski,ventre}@icsi.berkeley.edu

                      Fourth IEEE Workshop
                               on
         Future Trends in Distributed Computing Systems
                             Lisboa

                         September 1993


                            Abstract

A specific class of multimedia applications is expected to be  of
importance  for  future  communication  networks: Multi-Party In-
teractive Multimedia (MIM).  Based on the isolation  and  charac-
terization of MIM applications, concrete network support require-
ments are derived in this paper. The varying  degree  of  connec-
tivity,  the  vastly different sizes in terms of participants and
the reliance on a guaranteed Quality of Service make MIM  support
a  difficult  problem. Starting with the definition of multimedia
communication abstractions, principles of solutions are sketched.
For  an  important  subclass of applications a particularly effi-
cient and practicable alternative implementation based  on  half-
duplex  channels  is introduced.  Finally, interfaces at both the
transport and network layers are considered.