Multicast routing and resource allocation for high-speed networks

In recent years, a number of architectures (ATM, Next Generation Internet) have been proposed to provide real-time multimedia services over packet switched networks. Most of the emerging services need certain "quality of service" (QoS) guarantees from the network. Furthermore, many of these applications are multicast in nature. Five important components of the emerging network architecture supporting these applications are: Flow specification, Routing, Resource Reservation, Admission Control and Packet Scheduling. These components in conjunction try to meet the QoS requirements of a wide range of services. The goal is not just meeting QoS requirements of the applications but doing so efficiently. There is a strong interaction between various components of the architecture and hence the design of any component is based on certain assumptions about the remaining components of the architecture. This dissertation addresses the issues involved in the design of routing, resource allocation and call admission control components of the next generation Internet. The approach is however general in nature and applicable to any high speed integrated packet switched network. We particularly concentrate on guaranteed quality of service (GQoS) applications, defined by IETF (Internet Engineering Task Force), that need a firm end-to-end delay bound and no queuing loss for conforming packets. Conceptually we can think that a connection set-up process consists of two phases, though physical implementation may be different. In the first phase, a route is established from the source node to the destination node. The second phase consists of checking whether or not the application can be admitted along the route to meet the user's requirements. The success of the call admission phase depends on the amount of resources (buffer, bandwidth etc.) available in the selected route by the routing process in the first phase. A related issue is the mapping of end-to-end QoS requirement into local QoS requirements and then mapping local QoS requirements into resource requirements. In this dissertation, we first give an efficient and distributed algorithm based on the cost function (function of node utilization) to divide the end-to-end guaranteed QoS requirements into local QoS requirements. The simulation results show that the QoS division scheme based on cost function results in an efficient utilization of resources compared to the equal division scheme. We then select suitable routing metrics for GQoS applications in order to make an efficient use of network resources. We then give a heuristic approach that use these metrics to produce sub-optimum multicast trees. We also show that the resource reservation scheme given for uni-cast connections can also be used with multicast connections to do efficient resource reservation. We note that the key idea with both resource reservation and QoS routing is the efficient distribution of load across the network. Since both routing and resource reservation share the same goal, an efficient design is possible if these two problems are addressed concurrently. We show that the performance of a given resource reservation mechanism depends strongly on the underlying routing algorithm. Our simulation results show that the QoS routing algorithm proposed in this dissertation gives very good performance when used with cost based resource reservation scheme. We find that this is due to the even distribution of load across the network and minimal consumption of resources that result when this particular combination is used.