Lightpath rerouting scheme for dynamic traffic in WDM all-optical networks

This paper considers rerouting and minimization of incurred disruption due to rerouting in all-optical wavelength division multiplexed (WDM) network with dynamic (random) traffic arrivals and departures. One limitation of such a network is the wavelength continuity constraint imposed by the all-optical cross-connect switches which do not allow a circuit to be placed on a non wavelength-continuous route. Rerouting is proposed to rearrange certain existing lightpaths to create a wavelength-continuous route in order to accommodate a new connection request. Recently, a wavelength rerouting scheme called “Parallel Move-To-Vacant Wavelength Retuning (MTV-WR)” with many attractive features such as shorter disruption period and simple switching control has been proposed. In this paper, we propose a new lightpath rerouting scheme based on the “Parallel MTV-WR” rerouting scheme minimizing the rejection ratio whilst keeping a little service disruption period due to rerouting. We assume that a new random lightpath demand (RLD) arrives at time t and that its routing phase fails to set up it. To establish the new RLD the proposed algorithm tries to reroute one or several RLDs by only changing the used wavelength whilst keeping the same physical path in order to reduce the disruption period. If it fails, it tries to reroute a minimum number of active RLDs by changing the physical path and then possibly the used wavelengths. Simulation results show that our proposed algorithm computes a better rejection ratio than the rerouting algorithms previously presented in the literature while keeping a minimum number of rerouted lightpaths and a very small service disruption period.