Evaluating the Impact of Wavelength Conversion Cascading on the Performance of Optical Routing Algorithms

X. Gao, M.A. Bassiouni, and G. Li (USA)

Keywords

Alloptical networks, routing and wavelength assignment,wavelength conversion, conversion cascading constraint

Abstract

In this paper, we evaluate the negative impact of wavelength conversion cascading on the performance of all-optical routing. When data in a circuit-switched connection is routed all optically from source to destination, each wavelength conversion performed along the lightpath of the connection causes some signal-to noise deterioration. If the distortion of the signal quality becomes significant enough, the receiver would not be able to recover the original data. There is therefore an upper bound (threshold) on the number of wavelength conversions that a signal can go through when it is switched optically from its source to its destination. This constraint, we refer to as the conversion cascading constraint, has largely been ignored by previous performance evaluation studies on all-optical routing. We have performed extensive simulation studies to evaluate the blocking performance of optical routing algorithms in the presence of conversion cascading constraints. Our tests cover several network topologies including the U.S. Long Haul network, the ring topology, and the mesh-torus networks. The test results have shown that the blocking performance of optical routing deteriorates significantly under the impact of the conversion cascading constraint, especially when the connectivity of the network topology is relatively low. Therefore an effective routing & wavelength assignment (RWA) algorithm needs to take into account the impact of conversion cascading constraint to avoid the significantly reduced blocking performance it leads to.

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