Dynamic routing and wavelength assignment using learning automata technique [all optical networks]

Dynamic routing and wavelength assignment RWA is one of the most important issues in wavelength routed all optical networks. We introduce the learning automata technique for dynamic RWA in WDM networks without conversion under different load conditions. Learning automata are used to choose the shortest route from source to destination if more than one shortest route exist. Furthermore, learning automata are used to select which wavelength is to be used on the chosen route. We compare our wavelength assignment technique with some exhaustive wavelength assignment algorithms that scan all wavelengths on a predetermined shortest route. The use of the learning automata wavelength assignment technique reduces the call setup time by pursuing a small number of wavelengths. In addition, the technique is used to achieve fairness among different source/destination pairs. Simulation results are presented which indicate the benefits of using the learning automata technique for dynamic routing and wavelength assignment in WDM networks.

I. INTRODUCTION

Optical networks seem to have the answers for all problems in long haul and metro networking. They provide circuit-switched end-to-end optical channel or lightpath to the users. Using WDM, up to 80 (and more) separate wavelengths of data can be multiplexed into a light stream transmitted on a single optical fiber between network nodes. Communication via switching circuit in WDM implies that there is a dedicated lightpath between the source and the destination. This lightpath is a connected sequence of dedicated wavelengths on each link between the source and the destination nodes. Since we assume the network does not have conversion capabilities, the same wavelength must be available on all links belonging to the selected route. Routing and wavelength assignment RWA algorithms usually include a description of a procedure for finding a route and for selecting a wavelength to be used from the set of available wavelengths along that route. The objective of the RWA problem depends on the type of network traffic. The network traffic is either static or dynamic.