Study On Routing And Wavelengh Assignment Algorithm In Light-trail Networks

With the fast growth of IP services and the ultra large bandwidth provided by WDM (Wavelength Division Multiplexing) technology, the traditional optical network develops toward the next generation optical network-All Optical Network (AON). In AON, signals are transmitted in end-to-end all optical channels without electro-optical transformation.The AON takes the wavelength switching technology and the wavelength division multiplexing transmission technology as a foundation. At present, the wavelength switching technology have three kind of solutions which are the optical circuit swiching technology, the optical packet switching technology and the optical burst switching technology. All these technologies cannot enable IP burst service due to the limit of their technologies. Therefore, a new solution called light-trails has been proposed for catering to dynamic traffic in the optical domain. Routing and Wavelength Assignment (RWA) is one of the key problems in light-trails networks. So this paper mainly studies on dynamic RWA problem in Light-trail networks, i.e., the problem about how to create light trail and how to establish light connection dynamically.The light-trail is a unidirectional optical channel between any chosen source and destination node, which permits its middle nodes (in different time, time division multiplexing) to transmit traffic within it. Therefore, the light trail can effectively utilize the optical network's bandwidth resources. The 2nd chapter mainly introduces the light-trial networks's node structure, the light trail's establishment/demolition, and the maintenance and related signaling protocols, which will provide the rationale for the 3rd chapter and the 4th chapter. Moreover, the 2nd chapter gives a brief review about the up-to-date research results about the light-trail networks.Because the light trail has the drop-and-continue functionality for the signal passing it, the signal energy loss is very serious when the signal passes through the nodes in the light trail. Although the SOA can compensate the energy which the signal loses, the light trail's length is still restricted. The light trail's length can be represented by the physical hop number which light trail passes. In the 3rd chapter, we propose a light trail design algorithm based on length limit. We compare the performance of the algorithm by extensive simulations and study on the influence of the light trail's length.Although the RWA problem in WDM networks has received more attention, the current research on the light connection's design is at the initial stage. Overlapping of light connection in the light trail has reduced the utilization rate of light trail. In the 4th chapter, we will analyze the effective design of the light connection in the light-trail networks, and propose a dynamic light connection design algorithm based on priority.Lastly, we introduce the simulation platform used in this paper, and gives the simulation modules, program pseudo codes, and so on.