On the joint virtual path assignment and virtual circuit routing problem in ATM networks

Among different transport techniques proposed to implement B-ISDN, asynchronous transfer mode (ATM) is considered to be the most promising one and has been standardized by the CClTT due to its efficiency and flexibility. The use of virtual paths in ATM networks reduces the call set-up delays, simplifies the hardware in the transit nodes and provides simple virtual circuit admission control. However, it also reduces the degree of capacity sharing and, thus, increases the call blocking rate for most cases. In this paper, we consider the following problem: given a network topology, link capacity of each physical link, cell-level performance objectives and traffic requirement of each origin-destination pair, we want to jointly determine the following four design variables: (1) the node pairs that should have virtual paths, (2) the route of each virtual path, (3) the bandwidth assigned to each virtual path and (4) the routing assignment for each virtual circuit (call), to minimize the expected call blocking rate subject to call set-up time constraints. The problem is formulated as a nonlinear nondifferentiable combinatorial optimization problem and an efficient two-phase solution procedure is proposed. Experimental results are presented to show the trade-offs between throughput and call set-up time thresholds.