Fault-tolerant routing with non-adaptive wormhole algorithms in mesh networks

We present simple techniques to enhance the e-cube algorithm for fault-tolerant routing in mesh networks. These techniques are based on the concept of fault rings, which are formed using fault free nodes and links around each fault region. We use fault rings to enhance the e-cube to route messages in the presence of rectangular block faults. We show that if fault rings do not overlap with one another-the sets of links in fault rings are pairwise disjoint, then two virtual channels per physical channel are sufficient to make the e-cube tolerant to any number of faulty blocks. For more complex cases such as overlapping fault rings and faults on network boundaries, three or four virtual channels are used. In all cases, the routing guarantees livelock and deadlock free delivery of each and every message injected into the network. Our simulation results for isolated faults indicate that the proposed method provides acceptable performance with as many as 10 percent faulty links