Patent ID: 7574133

Claim:
A multi-node optical network comprising: a plurality of working paths configured for transmitting traffic signals in a first direction in an optical ring network; a normally inactive, singular, looped protection path in the network; a plurality of network nodes, coupled to the working paths and the looped protection path, at least one working path communicates traffic in the first direction between first and second nodes, from the second node to the first node; all nodes coupled to the protection path include a substantially identical recovery module with each module incorporating first and second monochromatic sources of light, one source is associated with the working path, the other is associated with the protection path, and at least one detector of monochromatic light received from the working path; control circuitry in each module coupled to the respective detector and sources, the control circuitry in the module at the first node detects a failure at the second node by detecting a loss of monochromatic light on at least a portion of the working path where the light originated at the second node, the control circuitry at the second node detects a loss of monochromatic light on at least a portion of the working path where the light originated at the first node, and the control circuitry at both nodes in response to the detected loss of light initiates a multi-step switching process to transfer traffic on at least a portion of the working path between the first and second nodes to at least a portion of the protection path between those nodes, the control circuitry at the first node transmitting a selected dataless control signal via the looped protection path to the second node, and the control circuitry at the second node, in response thereto, subsequently transferring traffic from a failed portion of the path, between the first and second nodes to a portion of the protection path therebetween for communicating the traffic from the failed portion of the path via the protection path in the first direction and wherein traffic from any one of the working paths can be switched to the looped protection path for transmission in the first direction in response to a failure of the respective working path while the remaining working paths continue to transmit signals in the first direction.