HIERARCHICAL DYNAMIC CONTROL OF MULTIPLE TRAFFIC CLASSES IN ATM NETWORKS

A hierarchical control structure is proposed to ensure performance req uirements and to maintain load balancing among different traffic class es at an ATM node. A two-level control hierarchy is defined, where one level performs fixed class-selective call admission control strategie s that are periodically dynamically coordinated by a higher level band width allocation controller. The call admission control rules are desi gned to maintain a certain grade of service, in terms of cell loss pro bability, given the buffer space and bandwidth (percentage of cells) a ssigned to each class. The assignment of buffers is performed off-line , whereas bandwidth shares are periodically recomputed on-line by the allocation controller, that attempts to minimize a cost function, acco unting for overall cell loss and refused traffic. The bandwidth assign ments obtained are passed to the call admission controllers, where the y are used as parameters affecting the admission rules until the next intervention. The control structure, the strategies and the optimizati on algorithm used are described in detail, as well as the assumptions underlying the choices that have been made. Simulation results are rep orted and discussed.