Protection and restoration scheme for light-trail WDM ring networks

In this paper we propose a protection strategy for light-trail (1-4) networks for ring topologies. A light-trail is a multi-point lightpath, such that multiple users can take part in communication along the trail, through time (differentiated) non-overlapping connections. Dynamic connections between source-destination pairs can be set up and torn down without the need for optical switch reconfiguration. A light-trail hence represents an opportunistic medium that reduces the uncertainty of provisioning resources for dynamic connections. However, this multi-point flow model leads to a new set of problems in the area of protecting and restoring light-trail based networks. Conventional link protection or path protection techniques are not sufficient for light-trails because of the potential of having multiple possible source-destination pairs in the same trail over time. In this paper we propose a hardware scheme to protect light-trails and further prove its correctness. Further, the scheme is implemented through a failed-traffic assignment algorithm. Subsequently we consider alternative heuristic schemes for implementing the protection scheme proposed. We simulate and compare the simulation results to an analytical model developed.