Fault-tolerant real-time communication in FDDI-based networks

FDDI-Based Reconfigurable Networks have an architecture that is suitable for delivering messages that have hard real-time constraints as well as certain fault-tolerance requirements. This architecture uses multiple FDDI networks to connect hosts and provides for automatic reconfiguration to maintain high network bandwidth in spite of faults. An important open problem is how resources in such networks should be managed in order to guarantee that the fault-tolerant real-time requirements of messages are met. This paper presents an efficient and practical solution to this problem. Our solution consists of off-line and on-line components. On-line management deals with run-time manipulation of messages and network resources. A message grouping approach simplifies on-line management. Off-line management deals with message grouping, bandwidth allocation and schedulability verification. Three approaches are investigated: spatial redundancy, temporal redundancy and an integrated approach. It is shown that the integrated approach has the best performance. Our solution is compatible with the FDDI and SAFENET standards