The Converter Placement in Wdm Network

1 Introduction In recent years, the increasing popularity of the Internet leads to a rapidly rising demand for network bandwidth. Optical networks offer much higher bandwidth than traditional networks due to huge bandwidth of fiber. The currently attracted technology to use effectively the bandwidth of optical fiber is wavelength division multiplexing WDM. The optical spectrum of is divided into a large number of channels on different wavelengths. WDM technology provides transmission on different optical wavelengths through the same optical fiber. We will deal with optical WDM networks only, where each data channel corresponds to a different wavelength. It is known as a circuit switched optical WDM network [1]. We also assume that the data still remain between two end nodes in the optical domain. Such a network is called all-optical or photonic networks [1]. The all optical WDM networks are still very popular for backbone networks with very high transmission rates. In WDM networks, data can be routed to their respective destinations based on their wavelengths. A network which employs this technique is known as a wavelength routed network [1]. In order to transfer data from a source node to end node, a wavelength continuous route has to be set up at the optical layer, which is called a lightpath. All lightpaths using the same fiber link must allocate different and distinct wavelengths. It is also known as distinct wavelength assignment constraint [1]. The WDM network consists of two types of nodes: • End nodes (access or edge nodes), which provide the interface between non-optical end systems and the optical systems. • Optical cross-connects (OXC), which connect the fibers in the networks and provide the switching and routing functions in order to establish the connection between edge nodes.