Reconfiguration based failure restoration in wavelength-routed WDM networks

Wavelength-division multiplexed (WDM) optical networks using wavelength routing are considered to be a potential candidate for next-generation wide-area backbone networks. The key component in such networks is the light-path network (LPN) manager. The functions of the LPN manager include setting up the logical topology, sustaining the network by monitoring traffic and network parameters, and handling node and/or link failures. Failure handling in WDM networks is of prime importance due to the nature and volume of traffic these network carry. Failure detection is usually achieved by exchanging control messages among nodes with timeout mechanisms. Failure restoration can be done either by re-routing only the failed light paths (LPs) or by reconfiguring all the existing LPs in the network. The reconfiguration approach involves finding new LPs in the faulty network (LP design) and realizing these new LPs by selectivity removing the old LPs (LP realization) with the objective of minimizing the service disruption to the ongoing calls. Existing work on the reconfiguration approach considers only LP design and ignores LP realization. In this paper, we first propose an architecture for the LPN manager highlighting the importance of LP realization in reconfiguration-based failure restoration, then we propose performance measures and heuristic algorithms for LP realization. We evaluate the effectiveness of the LP realization algorithms through simulation studies