Enhancing fault tolerance capabilities in quorum-based cycle routing
  In this paper we propose a generalized R redundancy cycle technique that provides optical networks almost fault-tolerant communications. More importantly, when applied using only single cycles rather than the standard paired cycles, the generalized R redundancy technique is shown to almost halve the necessary light-trail resources in the network while maintaining the fault-tolerance and dependability expected from cycle-based routing. For efficiency and distributed control, it is common in distributed systems and algorithms to group nodes into intersecting sets referred to as quorum sets. Optimal communication quorum sets forming optical cycles based on light-trails have been shown to flexibly and efficiently route both point-to-point and multipoint-to-multipoint traffic requests. Commonly cycle routing techniques will use pairs of cycles to achieve both routing and fault-tolerance, which uses substantial resources and creates the potential for underutilization. Instead, we intentionally utilize R redundancy within the quorum cycles for fault-tolerance such that every point-to-point communication pairs occur in at least R cycles. The result is a set of R = 3 redundant cycles with 93.23-99.34% fault coverage even with two simultaneous faults all while using 38.85-42.39% fewer resources. 
Cory J. Kleinheksel and Arun K. Somani
cs.NI