A Theory to Increase the Effective Redundancy in Wormhole Networks

Fault-tolerant systems aim at providing continuous operations in the presence of faults. Multicomputers rely on an interconnection network between processors to support the message-passing mechanism. Therefore, the reliability of the interconnection network is very important for the reliability of the whole system. This paper analyses the effective redundancy available in a wormhole network by combining connectivity and deadlock freedom. Redundancy is defined at the channel level, giving a sufficient condition for a channel to be redundant and computing the set of redundant channels. The redundancy level of the network is also defined, proposing a theorem that supplies a lower bound for it. Finally, a fault-tolerant routing algorithm based on the former theory is proposed.