Routing in packet switched computer communication networks

This thesis concerns the optimization of the routing path in packet-switched computer-communication networks. Computer-communication networks over the past decade are outlined. A glossary of some of the terms used throughout this thesis are introduced. A brief description follows of the advantages of packet switching over the more conventional circuit-switched scheme for information transfer. The important design variables that a network planner is faced with in the design of these networks are discussed. A general design problem is stated and then decomposed into simpler subproblems one of which is the link-capacity assignment problem, which is briefly discussed. The route-assignment problem is identified as being of particular importance and is specified. A network model is introduced and relationships between performance measures, input parameters and constraints that appear in the general design problem are discussed. The routing problem is the formulated and a heuristic routing procedure is suggested as a sub-optimum solution to the problem. Basic routing methods are discussed. The principles of datagram and virtual circuit techniques are explained with reference to the routing of packets throughout the network. The directory routing technique with alternate routing is identified as being a specific requirement and the operation of this technique is explained in more detail. Two basic algorithms are introduced. The first which determines the shortest, second shortest, third shortest, etc., paths between all pairs of nodes in a network. The second which determines from all the paths in the first algorithm, the best alternative paths between all pairs of nodes in a network. A heuristic routing algorithm for establishing routing tables at each of the individual nodes in a packet switched data network is presented. Among the properties of a desirable routing algorithm is that the paths established between all node pairs are such that the average packet delay from source to destination node is minimal. The heuristic-routing algorithm proposed is to-be implemented on a newly proposed SAPONET packet-switching network, with special emphasis on the minimization of the average packet delay of the network. Results are presented and discussed for different combinations of the primary, secondary, tertiary and fourth alternative paths obtained. Finally, results are summarized and areas for further work identified