Adaptive routing considering the number of available wavelengths in WDM networks

In most existing studies of wavelength-division multiplexing networks, the problems of routing and wavelength assignment are generally treated separately, since it is NP-complete to produce the optimal solutions for the two problems at the same time. Our four adaptive routing algorithms presented in this paper, however, consider the availability of wavelengths during the routing process. Our algorithms favor paths with near-maximum number of available wavelengths between two nodes, resulting in improved load balancing. Simulations show that our algorithms reduce call blocks nearly by half when compared with the least-loaded and the k-fixed routing algorithms in some small networks using the first-fit wavelength assignment policy. In addition, simulation and analysis show that the path length of our algorithms is almost the same as those of the other algorithms.