Bandwidth requirements of the internet are increasing every day. Wavelength Division Multiplexing (WDM) is the next step towards leveraging the capabilities of the optical fiber, especially for wide area backbone networks. Reconfiguration is a characteristic of WDM optical networks that allows network operators to arrange the networks in response to the changing traffic demands. As a general assumption, reconfiguration studies are based on the idea that the decision of reconfiguration is sudden, i.e. triggered by an event, hence the virtual topology change is an interrupted process. It has two objectives: finding routes that satisfy the wavelength assignment constraints, and making efficient use of network resources. The complexity involved in the networks may require the consideration of multiple constraints to make the decision. In this paper we proposed a new approach using fuzzy logic control on IP over WDM network to reconfigure virtual topology that allows multiple constraints to be considered in a simple and intuitive way. Five fuzzy sets for the number of deleted lightpaths and average utilization for each wavelength are used to divide the variable space: very high(VH), high(H), medium(M), low(L), very low(VL). Simulation shows that this fuzzy reconfiguration algorithm is efficient and promising.

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