Detection and Localization of Silent Failure Caused by WSS Forwarding Errors in Optical Networks

With the rapid development and wide application of optical networks, it is necessary to enhance their flexibility to meet the demands of various scenarios. Wavelength selective switches (WSSs), which allocate different wavelengths to different paths, are fundamental components for flexible and reliable transmission in optical networks. However, silent failure caused by WSS forwarding errors can lead to signals being transmitted to the wrong receiver without triggering alarms, resulting in prolonged transmission interruptions, which is unacceptable. In this paper, we propose a failure detection and localization scheme for silent failure caused by WSS forwarding errors. The scheme leverages the coherent receiver to detect and localize failures without the need for additional monitoring equipment, thereby reducing costs. Failure detection is achieved by calculating the transmission distance based on the dispersion estimation, and is complemented by node number calculation according to the narrow-band filtering effect. The failure localization algorithm is based on the actual path determined by this transmission distance. The simulation results of transmitting 30 GBaud PDM16QAM signals in NSFNet and GNet show that the failure detection accuracy in the examples reaches 100%, and the failure localization achieves a 90.48% and 90.20% reduction of the faulty node range in the two networks respectively. Furthermore, the results of transmitting multiple lightpaths in GNet validate the accuracy of our proposed scheme. To the best of our knowledge, it is the first time that the detection and localization scheme for silent failure has been validated in optical networks.