Connection-oriented real-time communication in ATM-based heterogeneous networks.

摘要

In this research, we study real-time communication in an ATM Based Heterogeneous Network (ABHN). ABHN is a heterogeneous network consisting of legacy LAN segments such as FDDI and IEEE 802.5 token ring network connected to an ATM backbone. In real-time communication, messages are delay sensitive and have deadlines associated with them. Connection-oriented communication is well suited for real-time communication which needs delay guarantees. In connection-oriented communication, a connection has to be admitted before data are transferred. During the connection admission process, Connection Admission Control (CAC) allocates resources to the connection and tests if the worst case delay of connections meets their respective deadlines. Thus, delay analysis and resource allocation are pivotal to the overall performance of the system.; ABHN consists of network devices with different scheduling policies and Medium Access Control (MAC) protocols. We use a decomposition approach to carry out delay analysis of a connection. In this approach, a connection is decomposed into servers representing the network devices it passes through and each server is analyzed separately. We use a periodic traffic description at the sender. As the traffic passes through different network devices, the shape of the traffic changes. We use the multi-line segment approximation method to describe traffic inside the network. Closed form worst case delay at individual servers is obtained using this method.; We design and analyze three different CAC methods that deal with resource allocation in different ways. These three CAC methods are feasible region method, partition based method, and feedback based method. We discuss the advantages and disadvantages of these methods and evaluate their performance in terms of admission probability and execution time.; This dissertation provides an extensive study on real-time communication in ABHN. Most of the previous work in this area has concentrated on delay analysis and resource allocation in a homogeneous network environment like ATM-only or FDDI-only network. We have provided delay analysis and various CAC methods for real-time communication when these LAN segments coexist in the network. Our solution is compatible with the existing standards and can be implemented on commercially available hardware and software.