New architectures for diversity in fiber loop networks

Active and passive multiplexing technologies and alternative architectural approaches to diverse routing for fiber-loop networks are described. It is shown on the basis of Markov models that the mean time to failure (MTTF) for a 1:1 protected system can be significantly improved by deploying fiber with alternate paths and duplicate central offices. Specific network examples are used to compare installed first costs of the active and passive multiplexing alternatives for various loop-diversity approaches. The results indicate the requirements for diverse routing can have a large impact on the choice of technologies and approaches for fiber loop networks. Specifically, a passive double-star architecture, using dense wavelength-division multiplexing (WDM) techniques, represents a promising technological approach to diverse routing, for it has the lowest installed first cost for diversity in the loop of the several approaches studied, both in suburban and urban areas.<>