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Abstract. In this paper we consider the wavelength requirement for all-optical networks based on wavelengthdivision multiplexing (WDM). Given a static channel demand, the problem of routing and wavelength assignment (RWA) in such networks has to be solved. Due to the restricted number of wavelengths available on each link it is desirable to get a solution of the RWA problem, in which the needed number of wavelengths is minimized. Unfortunately, this optimization problem belongs to the class of NP-complete problems. Therefore in this paper we present a new powerful method for the approximative solution of the RWA problem. This new approach is based on the combination of a genetic algorithm and a quite simple heuristic. The efficiency of this combined algorithm is demonstrated by the application to some well known benchmark problems.

We describe in this paper how the backbone network of a major German telecommunication company has been globally optimized using the so-called branch-and-bound algorithm. The described optimization approach enables significant reductions of expenses for leased lines compared to manually derived planning results. This gain achieved by the presented optimization approach is also demonstrated by the comparison with a heuristic algorithm which is used for the simulation of a human network planning process.

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