In WDM networks, the end users exchange information with each other through all optical WDM
channels, called light-paths. A light-path must occupy the same wavelength on all the fiber links
through which it traverses. In a WDM optical network, with
a given set of connections, the
question of setting up light-paths by routing and allocating a wavelength to each connection is
called Routing and Wavelength Assignment (RWA) problem. Integer Linear Programming (ILP) is
a mathematical formulation helps in minimizing and maximizing an object function under multiple
constraints. This can help in formulating a mathematical model for RWA. This paper studies a
mathematical model for RWA in WDM Optical networks which can lead to a good network
planning. This paper suggests an enhancement proposal for Syrian telecommunication optical
networks using ILP formulation.