Virtual path assignment in atm networks

In this thesis, we address the problem of assigning virtual paths in Asynchronous Transfer Mode (ATM) networks. Virtual Path (VP) Assignment is an important resource and traffic management activity in ATM networks. By using the VP concept, the logical layout of the network can be administered to minimize the total network cost to the provider and to achieve specified quality of service (QoS) for users. We formulate the VP Assignment problem as a constrained optimization problem; the objective function to be minimized reflects processing/control costs at nodes and transmission costs between nodes. The blocking probability quality of service (QoS) requirements and overall throughput of the network are taken into consideration in the solution process as constraints. Since the solution space is complex, we first develop a deterministic, iterative heuristic algorithm (VPA-F) to reach a “near-optimal” VP configuration for a given physical network and traffic demand with fixed-routes. The VPA-F algorithm assumes that connection routes in the physical network are given. The Multi-Rate Loss Network model is used in the calculation of connection-level blocking probabilities. An innovative VP capacity allocation procedure is designed based on max-min fairness principle in order to meet the accuracy and computation-time goals. The heuristic algorithm is expanded to include the assignment of variable connection routes. The connection routing is incorporated into the optimization algorithm (VPA) by applying a rerouting heuristic for traffic streams. Results of runs of the VPA-F algorithm are presented, for various forms of the objective function and constraints. The minimum number of VP hops objective is found to be the most suitable for a fixed capacity network. The VPA algorithm (with variable connection routing) is tested with this objective function, and its performance is compared to VPA-F.