Patent ID: 7706690

Claim:
A relay node used in a WDM optical network, comprising: a high-speed side port configured to add/drop optical signals of various wavelengths; a low-speed side port configured to add/drop optical signals of a single wavelength; a unit configured to generate a checking message for requesting another node to report constraint information of a low-speed side port of the another node, wherein the constraint information relates to adding an optical signal from the low-speed side port to a high-speed side port of the another node or dropping an optical signal from the high-speed side port to the low-speed side port of the another node; a unit configured to generate a response message including the constraint information of the own node in response to receiving the checking message sent from another node; and a storing unit configured to store at least the constraint information of the another node; wherein the constraint information includes information on wavelength of the optical signal that can be added/dropped by the high-speed side port and the low-speed side port.