Abstract: The one-way reservation protocol used in Optical Burst Switching(OBS) makes current routing and wavelength assignment(RWA) algorithms suffer from high burst blocking probability. In this paper, the logical topology of the OBS network is introduced to guide the lightpath establishment of the bursts, and an RWA algorithm based on virtual topology is given. The logical topology design problem is formulated as an integer linear programming(ILP), whose optimization objective is to maximize the carried load of the logical topology. Numerical results obtained for NSFNET show that our algorithm can not only balance the carried load on fiber links, but also reduce burst blocking probability. Moreover, it can reduce the number of used wavelength conversions greatly when the traffic load is not very high.

Key words: optical burst switching, logical topology, routing and wavelength assignment