Guaranteed Message Delivery Time on Real-Time Distributed Systems

Real-time systems require guaranteed timely delivery of messages; failure to deliver a message on time may result in failure of the system and possible damage to life and property. We describe here an extension and implementation of an algorithm developed by Kandlur et al. for guaranteed message delivery. We extend this by adding two-phase randomized routing in the channel establishment procedure; this scheme requires each route to go first to a randomly chosen intermediate node, and only then to its actual destination. This scheme balances the load demonstrably better than direct routing, with respect to the likelihood of acceptance of each individual channel. Given certain constraints on the generation and size of messages, it is possible to schedule those messages such that messages arrive within their desired deadlines. Experiments on an 8-node network demonstrate the feasibility of the approach, and provide verification of Kandlur’s algorithm.