Exact Admission Control for Networks with a Bounded Delay Service
Jorg Liebeherr
Dallas E. Wrege
Department of Computer Science
University of Virginia
Charlottesville, VA 22903
Domenico Ferrari
University of California at Berkeley
and International Computer Science Institute
1947 Center St., Suite 600
Berkeley, CA 94704-1105
Abstract
To support the requirements for the transmission of continuous media,
such as audio and video, multiservice packet switching networks must provide
service guarantees to connections, including guarantees
on throughput, network delays, and network delay variations.
For the most demanding applications, the network must offer a service
which can provide deterministic guarantees
for the maximum delay of packets from all connections,
referred to as bounded delay service.
The admission control functions in a network with a bounded delay
service must have available {\em schedulability conditions}
that detect violations of delay guarantees in a network switch.
In this study, exact schedulability conditions are
presented for packet switches which transmit packets based on an
Earliest-Deadline-First (EDF) or a Static-Priority (SP) algorithm.
The schedulability conditions are given in terms of a general traffic
model, making the conditions applicable to a large class of traffic
specifications.
A comparison of the new schedulability conditions with existing, less
accurate, conditions show the efficiency gain obtained by using exact
conditions.
Examples are presented that show how the selection of a particular
traffic specification and a schedulability condition impact the
efficiency of a bounded delay service.