A four-fiber optical channel shared protection ring with both ring and span switching is demonstrated experimentally. The ring employs a node architecture using 4x4 and 1x2 optical switch fabrics to perform add/drop and protection switching functions. To coordinate the protection switching process, a new APS signaling protocol is developed with messages transmitted through an OSC. Control hardware and software for the APS controller, fault detectors and switch fabric controllers are implemented. For a single channel system with four nodes, ring and span protection switching times of about 10 ms and revert-to-normal switching times of about 5-7 ms are experimentally demonstrated. Results from protection scaling experiment show that the protection switching time increases linearly with the number of node and number of channels. A typical regional long haul ring network with 8 nodes and 1200-km circumference can protect up to 80 wavelength channels in less than 50 ms.
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