Routing and Wavelength Assignment Schemes in WDM Optical Networks

All optical networks using wavelength-division-multiplexing (WDM) technology are promising for serving as the backbone of next generation Internet, because optical WDM networks can provide huge bandwidth capacity. Given a set of connection requests, the routing and wavelength assignment (RWA) problem involves finding a route (routing) and assigning a wavelength to each request. The RWA problem is usually divided into two types: static RWA and dynamic RWA. In the static RWA problem, the entire set of connections is known in advance, and the problem is to set up light paths for these connections so that used network resources are minimized. In the dynamic RWA problem, since connection requests arrive randomly, it is more difficult to solve. Combined routing and wavelength assignment Although is a hard problem, it can be simplified by separate into two sub problems: the routing sub problem and the wavelength assignment sub problem.  In this paper we gave an overview of well-known routing schemes, advantages and disadvantages of several functional characteristics are discussed. We also briefly consider the characteristics of wavelength-converted networks (which do not have the wavelength-continuity constraint).