Hitless Switching in a Data-centric WDM Optical Network

This paper proposes a methodology for reconfiguring a Wavelength Division Multiplexed (WDM) optical network to adapt to changing traffic requirements at the Asynchronous Transfer Mode (ATM) layer. The ATM network layer in turn is reconfigured to adapt to changes in traffic patterns. These changing ATM network topologies, or connectivities, are known and are used to design the network. The proposed method sizes the ATM switches and then assigns wavelengths between pairs of ports at the switches in order to support the required ATM network topologies and their reconfiguration in a hitless manner. The ATM switches are sized at each node so that they can support the union of an ATM topology and the next topology to which it reconfigures. Upper and lower bounds on the number of wavelengths needed at the WDM layer for such a hitless reconfiguration are found and two wavelength assignment heuristic algorithms are proposed. These heuristic algorithms are then implemented and their results are compared with the lower and upper bounds.