| The advent of the Internet followed by the accelerated macro-evolution of the World Wide Web (WWW) has profoundly altered our lives. As end users, we perceive only the end to end flow of information. Internet Service Providers (ISPs) have embraced the vision of a broadband Internet, which can use the same infrastructure to cost-effectively multiplex voice, video, and data traffic. They have to constantly manage and monitor their networks in order to deliver seamless end to end services to us, their users. Network state models are tools used by the ISPs for carrying out the above functions. In this dissertation, we propose two network state models, one for state aggregation for inter-domain QoS routing, and the other for network performance analysis.; For state aggregation in QoS routing, we have developed models that capture accurately the resource availability in a domain. More specifically, we propose to use the routing capacity of a domain as an aggregate metric, and use network flows for estimating the same. We extend our model to stochastic networks, and discuss the problem of finding the ‘max-flow’ in such stochastic networks. We propose a fast approximate algorithm for solving the above problem. We also propose a new performance measure called “Aggregated Accuracy Index” for measuring the accuracy of the aggregation schemes.; For analyzing the performance of networks, we have modeled the network as a finite shared resource, more specifically as a multi-dimensional loss system with bursty call arrival processes. We have solved for the approximate steady state distribution of the above system. This has been an open problem since 1981. It is well known that the actual call arrival processes in the network are bursty in nature. Hence our model aims to realistically capture the operating characteristics of the network. |
