Design of an efficient and practical algorithm for wavelength assignment in multi-wavelength ring transport networks

This paper describes the design of an efficient and practical algorithm for the problem of wavelength assignment in all-optical wavelength routed ring networks. A mathematical model which provides an optimal solution to the problem is described and compared with two other simpler techniques which are based on heuristic algorithms. These two heuristic methods are specifically designed for ring networks and their performance is evaluated on several traffic loads and patterns so as to understand the merits of them under different problem scenarios. It is found that sorting the traffic connections according to their respective shortest path lengths before establishing them can be very useful in certain traffic conditions, but does not necessarily result in efficient wavelength assignments for all problems. The iterative improvement scheme presented is found effective and robust as good results for various traffic scenarios can be achieved within reasonable time, and thus are considered useful for practical implementation. In contrast, the purely mathematical approach is limited in that it is only applicable to small to medium problem sizes due to the excessive demands of computational time.