Multiplexing Real-Time Channels


                     Spiridon Damaskos
9   Gesellschaft fur Mathematik und Datenverarbeitung mbH
                    Berlin, West Germany

                       Dinesh C.Verma
9                 Computer Science Division
                      EECS Department
                  University of California
        and International Computer Science Institute
                    Berkeley, California




                          Abstract


     A real-time channel is a simplex connection between two
nodes  characterized  by parameters representing the perfor-
mance requirements of the client. Such a connection  may  be
established  through  the  scheme  described in [Fer89a]. In
this paper, we study the feasibility of  multiplexing  real-
time channels on a lower-layer real-time channel. Sufficient
conditions for multiplexing  channels  are  obtained  as  an
extension of the establishment algorithm.

     The extension is  based  on  two  observations:  (1)  a
real-time  channel  can  be  looked  upon  as a network with
bounded delays connecting the multiplexing point (a  virtual
source) to the demultiplexing point (a virtual destination);
and the parameters of the physical channel can  be  used  to
define  the  service  time  at  the virtual source and sink.
Multiplexing is nothing but channel establishment over  this
network.   By a judicious definition of the parameter speci-
fying service times, it is  possible  to  make  multiplexing
decisions  at  the  multiplexing point (source) without con-
sulting the destination, which is merely informed about  the
new multiplexed channel.