A connection node is included in a connecting part of a plurality of rings in a ring network. The connection node includes a failure detecting unit, an optical-signal processing unit, an ODU switch, and an optical-signal processing unit. The failure detecting unit detects failure in the connecting part. The optical-signal processing unit receives data transmitted from another node on a ring to which the connection node belongs. Upon detection of the failure, the ODU switch determines whether to pass the data or return the data in reverse direction from the connection node depending on a destination to transfer the received data, and sets a transmission path of the data based on a result of the determination. The optical-signal processing unit transfers the data in accordance with the set transmission path.