Fault tolerance design for large-scale optical switches

In this paper, we present an enhanced fault tolerance in large-scale optical switches through innovations in architecture and control logic design. A large-scale switch is constructed from a network of 2×2 optical switch elements (SEs). Classic switch network architectures, such as the Benes, are not designed with fault tolerance in mind. There are three major contributions in this paper: (1) we developed an analytical method, referred to as the probability accumulation method, to calculate the average connection blocking probability in a faulty switch network; (2) we provided a failure-aware routing algorithm to effectively circumvent connections from defected SEs in a dilated Benes switch; and (3) we improved the connectivity pattern of the Benes network to further reduce the blocking probability, especially when the SE failure rate is low.