Performance evaluation of a local area network for real-time applications

This paper presents the performance (upper bound for the transmission waiting time, capacity, expected message delay and loss) of a controlled access protocol for real time LANs. The protocol guarantees mutual exclusion for the access to the transmission medium, upper bound for the transmission waiting time and priority management. The expected message delay, obtained by simulations, is compared to the delays of some of the best or most widely used protocols: token ring, token bus, MiniSlotted Alternating Priorities, and to M/D/1 which represents an upper bound on performance. End to end response time has also been evaluated for a case study to point out the influence of scheduling, communication architecture and application software, and to obtain data for the design of real-time systems based on the examined LAN. For each LAN node, hardware architectures based on one or two processors have been considered and the main differences with reference to their performance have been pointed out