Real-time communication using fddi-based networks

This dissertation addresses some of the problems and issues in providing real-time communication services in high speed networks such as the FDDI. It has become a common practice to use digital computers for embedded real-time distributed applications such as space vehicle systems, image processing and transmission, and the integration of expert systems into avionics and industrial process control. A salient feature of these computations is that they have stringent timing requirements. A failure to meet the computational deadlines could lead to a catastrophe. Further, these real-time systems are often distributed. This is because (1) the applications themselves are often physically distributed and (2) distributed systems can very often provide better reliability, resource sharing, and extensibility. This study concentrates on designing algorithms for communication and providing fault-tolerance in high speed networks. It also addresses architectural implementation issues, fault management issues, traffic characterization and resource management issues in real-time communication networks. With the ever growing demand for multi-media services and Quality-of-Service guarantees on the internet, it has become increasingly important that current technologies such as FDDI and ATM (both high speed networking technologies) be studied in the context of the above goals. This dissertation study focuses on FDDI based networks primarily because it has been already established as a mature technology and is used as the back-bone of several large campus networks. This study makes several “first-time” contributions. The existing timing properties (published prior to this study) of FDDI networks have been further generalized. Further, this study also identifies conditions for meeting real-time communication constraints in FDDI. The design and analysis of several bandwidth allocation algorithms and implementation issues regarding bandwidth allocation in FDDI is also discussed. Further, the design of fault-tolerant FDDI based ‘reconfigurable’ networks (FBRN) is generalized. This study also presents algorithms for reconfiguration of the FBRNs. Finally, extensions to FDDI hardware and Firmware needed to implement the FBRN is outlined in this study.