Patent ID: 7424220
Filing Date: 2008-09-09
Classification: H04J

Abstract:
1. An optical transmission system transporting optical signals over a ring network with wavelength-division multiplexing (WDM) techniques, the system comprising: (a) a plurality of optical transmission devices, each comprising: a transponder that converts a high-priority client signal and a low-priority client signal into a high-priority wavelength signal and a low-priority wavelength signal to be added to network traffic, a device manager that manages network failure information and lightpath information of the ring network, and an optical switch fabric that normally delivers the high-priority wavelength signal to a high-priority path and the low-priority wavelength signal to a low-priority path running in an opposite direction to the high-priority path, and when a network failure is encountered, performs protection switching in either duplicate switching mode or path switchover mode depending on the network failure information and drop wavelengths of each optical transmission device; and (b) transmission media interconnecting said plurality of optical transmission devices in a ring topology; wherein: the high-priority client signal, high-priority wavelength signal, and high-priority path have higher priority than the low-priority client signal, low-priority wavelength signal, and low-priority path, respectively, in terms of survivability against network failure, the duplicate switching mode directs the high-priority wavelength signal to both the high-priority and low-priority paths, and the path switchover mode directs the high-priority wavelength signal to the low-priority path, instead of the high-priority path; and wherein said device manager comprises: a failed wavelength map associating possible failure points on the ring network with wavelengths that could be disrupted as a result of failure at each stated failure point; a drop wavelength table describing wavelengths dropped locally at each optical transmission device; and a switching mode table specifying which of the duplicate switching mode and path switchover mode should be used when a network failure occurs to a wavelength described in the drop wavelength table.