In wavelength-division-multiplexing (WDM) optical networks, the failure of network elements (e.g. fiber links and cross connects) may cause the failure of several optical channels, thereby leading to data loss. This study examines different approaches to protect a mesh-based WDM optical network from singe-link failures. We utilize three existing models for protection and propose a new one. The models are based on dedicated and shared protection schemes. For dedicated protection we use dedicated- path protection, while for shared protection we use shared-path and shared-link protection. The proposed scheme is a subpath model (intermediate approach between shared-path and shared-link protection) and it is referred to as the SPL scheme.
Numerical results obtained for a representative network topology with random traffic demands demonstrate that the best and the worst model to save network resources are shared-path protection and dedicated-path protection, respectively. The resource utilization for the proposed model SPL and for the shared-link protection fall between the aforementioned cases and have similar performance.
We formulate models for protection-switching times for each of the models based on a fully distributed control network. We show that the protection switching process for dedicated-path protection is the fastest, closely followed by the results of SPL and shared-link protection schemes. The protection switching process for shared-path protection scheme is the slowest.
Finally, we performed initial tests in a representative network to observe the dynamic behavior of the models under a sequence of demand requests. The blocking rate found in the network while using each of the protection schemes was observed for different levels of network load. In order of increasing blocking rate to incoming demands, the protection models behave as follows: shared-path, shared-link, SPL and dedicated-path protection.