Abstract: The assignment of wavelength in the design of opticalpath layer of wavelength-routed network is discussed and a new mathematical description is proposed. According to the characteristics of the wavelength-routed optical network and the concept of pathgraph, a new algorithm for wavelength assignment is proposed.The assignment of wavelength is result fromthe resolve of the vertices coloring problem of the pathgraph. Simulation on computer is carry out to compare this algorithm with a used one on random network, the higher wavelength efficiency is acquired by new algorithm . This algorithmcan be used to exploit the wavelength resources effectively under the conditionof static services.

Key words: wavelength division multiplexing, wavelength routed optical networks, wavelength assignment algorithm