Technologies and approaches for diversity in fiber loop networks

The authors discuss active and passive multiplexing technologies and alternative architectural approaches to diverse routing to increase the availability in fiber networks. The focus is on ways of achieving diversity when fiber is deployed in the subscriber loop. It is shown that the availability for a 1:1 protected system can be improved significantly by deploying fiber with alternate paths and duplicate nodes. Using specific network examples, the authors compare installed first costs of the active and passive multiplexing alternatives for various loop-diversity approaches. The results indicate that requirements for diverse routing may 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 techniques has the lowest installed first cost for loop diversity for every model network studied.