Adaptive fault-tolerant wormhole routing algorithms with low virtual channel requirements

We present simple methods to enhance a recently proposed class of fully adaptive algorithms for fault tolerant wormhole routing. These algorithms are based on J. Duato´s (1993) theory and are being used in several research projects. We show that with three virtual channels per physical channel, multiple rectangular shaped fault blocks can be tolerated in two dimensional meshes. There is no restriction on the number of faults, and maintaining fault information locally is sufficient. The logic for fault tolerant routing is used only in the presence of faults, and there is no performance degradation in the absence of faults. The proposed technique incorporates fault tolerance into wormhole algorithms with simple logic and low virtual channel requirements