Patent ID: 7701847

Claim:
An inter-card channel protection method in a wavelength division multiplexed (WDM) system, the method comprising the steps of: at a transmitting end, dividing signals from a client side via a coupler into two paths which are sent to a first primary card and a first standby card, respectively, and sending the two paths of signal transmitted by the two cards via different routes to a receiving end; at the receiving end, the two paths of signal entering a second primary card and a second standby card, respectively, and the second primary card and the second standby card communicating with each other directly with the second standby card submitting the signal quality to the second primary card and the second primary card making a selection based on the submitted signal quality and the signal quality of its own, thereby deciding whether the second primary card or the second standby card is selected to work, the selected path of signal of the two cards being transmitted down to a client side, wherein a supported local switching request comprises in an order of a priority from the highest to the lowest: (1) clear; (2) card absent; (3) lockout; (4) forced switch; (5) signal fail; (6) signal degrade; (7) manual switch; (8) wait to restore; and, (9) no request; and, wherein the switching request with the higher priority may override the request with the lower priority.