Design of tunnel-based protection schemes in multigranularity optical cross-connect networks

As the technology advances to increase the number of wavelengths in fiber links, multigranularity optical cross-connects (MG-OXCs) have emerged as a solution to reduce the manufacturing cost of the traditional optical cross-connects (OXCs). In this paper, we aim to provide an efficient fault-recovery protection scheme for the lightpaths in the MG-OXC networks. A segment-based protection scheme, called tunnel based segment protection (TSP) is proposed to recover the communications interrupted by a fiber cut. TSP first allocates all the tunnels off-line according to the historical traffic matrix and then starts to serve the incoming requests. When allocating a tunnel, a backup tunnel is always allocated as well. Consequently, a lightpath is naturally divided into segments according to the switching types along the path. Therefore, after a working path is found for a connection request, only a shared backup path for those segments in the corresponding wavelength-switching layers need to be found. In addition, TSP utilizes wavelength-switching ports efficiently since working and backup tunnels can share the same wavelength-switching ports at two ends of the tunnel. Simulation results show that the network performance is improved comparing to adapt a straightforward path protection scheme for MG-OXC networks.