Resource allocation for quality of service provision in buffered crossbar switches

We consider the problem of allocation of resources within a buffered crossbar switch with credit-based flow control to support quality of service for traffic flows in the Internet. Specifically, we assume there is a collection of classes of service, each characterized by a strict delay upper bound that applies across all packets of the class. Flows entering the switch are characterized by arrival curves, and the switch must achieve delay objectives subject to the arrival curves. We develop a technique for determining the amount of bandwidth and the number of credits that must be allocated to a flow in order to guarantee its delay requirements. This technique also provides the basis for analyzing the maximum traffic handling capacity of a switch. We provide numerical examples that illustrate the application of our techniques. Finally, we discuss the performance of buffered crossbar switches having finite buffers with respect to that of output buffered switches under the same class of scheduling regimes.