Recent advances in optical wavelength division multiplexing (WDM) and optical switching have enabled the development of next generation computer networks, to operate at several Terabits per second. A side impact of this development is that fault tolerance has become even more important, since a single failure may now result in much greater loss of information. The proposed research will investigate critical problems in the design of survivable optical wavelength division multiplexed (WDM) networks that are based on mesh topology. The novelty of the proposed work is two-fold: first is the consideration of wavelength-sharing wavelength routed networks (WRWS), where multiple individual sessions may share a wavelength, and the second is consideration of multiple simultaneous link failures. The goal is to provide reliable connections, based on deterministic and probabilistic requirements, to the clients using the network. This topic constitutes an important component of the nation's critical infrastructure protection, given that optical WDM networks are fast becoming part of the high-speed national wide-area backbone infrastructure. The underlying goal is to obtain practical and tractable optimal and near-optimal solutions for networks with a large number of nodes (50 - 100), with several fibers per link and more than 100 wavelengths per fiber; an additional objective is achieving sub-millisecond restoration times, compared to the few-seconds solutions of today. The proposed research will address the performance comparison and cost-benefit tradeoffs of wavelength-sharing and optical burst switching (OBS) mechanisms.