As traffic on telecommunication networks continues to grow driven by increasing demand for voice and data communication services, the optical layer needs to provide functionalities such as lightpaths set-up and tear-down, protection and rerouting. This thesis mainly focuses on all-optical lightpaths establishment. We consider all along the thesis single fiber optical networks with finite resources, that is with a given amount of wavelengths per fiber-links. We present a suite of methods for optimizing design and for analyzing rejection ratios in all-optical WDM networks. Both exact and approximate optimization techniques are considered. The methods are assessed through various experiments and are shown to produce good results and to be able to scale up to networks of realistic sizes.