Distributed route selection for establishing real-time channels

To guarantee the delivery of real-time messages before their deadline, a real-time channel or connection must be established before the transmission of any message belonging to the connection. During this channel establishment phase, one must first select a route between the source and destination of this channel and then reserve sufficient resources along this route so that the worst-case end-to-end delay over the selected route may not exceed the user-specified delay bound. We propose an efficient distributed route selection scheme that is guaranteed to find a "qualified" route, if any, satisfying the performance requirement of the requested channel without compromising any of the existing guarantees. The proposed scheme can also eliminate the common reliability/performance bottleneck of a centralized route selection scheme while improving efficiency over the centralized and other distributed schemes. Although the proposed solution starts with searching all possible routes in parallel, it prunes infeasible routes quickly, and its worst-case operational overhead is shown to be only a linear function of the number of links in the network. Several examples and simulation results are presented to demonstrate the effectiveness of the proposed distributed route selection scheme as compared to sequential route-search schemes.