REAL-TIME COMMUNICATION IN A PACKET-SWITCHING NETWORK


            Domenico Ferrari and Dinesh C. Verma
                 Computer Science Division
 Department of Electrical Engineering and Computer Sciences
                  University of California
        and International Computer Science Institute
                Berkeley, California, U.S.A.










                          Abstract

     Broadband  integrated  networks  will  have  to   offer
real-time communication services; that is, they will have to
transport information with performance guarantees.  A  real-
time  service is defined as one capable of providing connec-
tions with performance guarantees (the  real-time  channels)
on demand and ensuring that the guarantees are always satis-
fied. These guarantees can be  of  various  types,  e.g.,  a
lower  bound  on  the  throughput  of a connection, an upper
bound on delays and delay variation experienced by a  packet
on a channel, or an upper bound on the packet loss rate.


     In this paper, we study the  feasibility  of  providing
real-time  services  on  a packet-switched store-and-forward
wide-area network  with  general  topology.  We  describe  a
scheme  for the establishment of channels with deterministic
or statistical delay and delay variation bounds and  bounded
loss rates, and present the results of the simulation exper-
iments we ran to evaluate it. The results  are  encouraging:
our  approach  satisfies  the  guarantees even in worst-case
situations, uses the network's resources to a  fair  extent,
and  efficiently  handles channels with a variety of offered
load  and  burstiness  characteristics.  Also,  the   packet
transmission  overhead  is quite low, and the channel estab-
lishment overhead is small enough to be acceptable  in  most
cases.