Patent ID: 8213790

Claim:
A method for 1+1 protection of an optical transmission path, the method comprising: (a) transmitting a first optical transmission signal from a first terminal node at a first end of the optical transmission path to a second terminal node at a second end of the optical transmission path, the transmission occurring in a working mode via a working path; (b) switching the optical transmission path from the working mode to a protection mode in the case of an interruption in the transmission of the first optical transmission signal via the working path, the protection mode enabling the first optical transmission signal to be transmitted via a protection path connecting the first terminal node to the second terminal node, the protection path being separate from the working path; (c) splitting the first optical transmission signal in the first terminal node, and feeding the first optical transmission signal to both the working path and the protection path; (d) disabling, in the working mode, a protection-path connection node, the protection-path connection node adapted to be enabled or disabled so as to respectively transmit or disallow the first optical transmission signal fed to the protection-path connection node from the first terminal node in the direction toward the second terminal node; (e) splitting the first optical transmission signal received at the second terminal node into a first optical sub-signal and a second optical sub-signal; (f) processing the first optical sub-signal in the second terminal node as a first reception signal; (g) feeding the second optical sub-signal as an east-side working-path control signal via the protection path to the protection-path connection node; and (h) detecting, in the protection-path connection node, whether the east-side working-path control signal is absent, the absence of the east-side working-path control signal being a necessary condition to enable the protection-path connection node to transmit the first optical transmission signal via the protection-path connection node in the direction toward the second terminal node.