Routing and wavelength assignment algorithms for WDM networks

Abstract

The Internet traffic and on-line e-business are growing all day and night, how to support the rapidly growing bandwidth demand and different Quality of Service (QoS) requirements has become an important issue. Wavelength Division Multiplexing (WDM) is an important technique to exploit the huge bandwidth of the optical fiber. There has been a wide deployment of WDM transmission technology in today s optical networks. WDM is based on the transmission of several light beams of different wavelength simultaneously through an optical fiber. A wavelength typically operates in hundreds of Mbps or even Gbps needs to be utilized better if the connection request is less than 100 Mbps bandwidth, otherwise there is a tremendous wastage of bandwidth in a fiber for data transmission. Though the fiber bandwidth has been improved due to the advancements in fiber-optic technologies and the increase in number of wavelengths in a fiber, there has not been much research in the area of fault tolerance, routing and wavelength assignment. These technologies are becoming a technology-of-choice to meet the ever-increasing demand for high-bandwidth. The large usable bandwidth (nearly 50 THz), reduced processing cost, protocol transparency, low bit-error rates and effective network component failure handling are some of the important advantages which have made wavelength routed WDM optical networks a standard for high-speed transport networks. A WDM optical network consists of wavelength routing nodes interconnected by optical fiber links in an arbitrary topology. In these networks a message can be sent from one node to another node using a wavelength continuous path called a lightpath and is uniquely identified by a physical route and a wavelength. It is required that the same wavelength should be used on all the links along the selected route and this constraint is known as the wavelength continuity constraint. Typically the traffic demand in these networks can be static, dynamic or scheduled.