A Novel Timer-Based Hybrid Rerouting Algorithm for Improving Resource Utilization Efficiency and Shortening the Incurred Service Disruption Period in WDM Transparent Optical Networks

In this paper we investigate hybrid rerouting and minimization of incurred service disruption period due to rerouting in Wavelength Division Multiplexed (WDM) transparent optical network. One limitation of such a network is the wavelength continuity constraint which does not allow a circuit to be placed on a non wavelength-continuous route. The impact of this constraint might have a severe consequence on the performance of transparent optical networks especially in terms of rejection ratio ant it is especially severe when traffic demands are unpredictable and characterized by random arrivals and departures. To alleviate the impact of these constraints, either wavelength conversion or traffic rerouting can be used. Since, in the foreseeable future, wavelength conversion is expected to remain an expensive technology, traffic rerouting is an attractive alternative solution. Thus, we here propose to employ hybrid rerouting to improve the network performances. Hybrid rerouting combines passive and active rerouting. Through simulation results, the performances of the proposed algorithm in terms of rejection ratio are demonstrated to be promising while rerouting a small number of already established lightpaths using Lightpath ReRouting (LRR). By rerouting a small number of existing lightpaths using LRR, we hope that the incurred service disruption period due to rerouting is minimized.