Abstract: A communication device includes: a switching unit connected to a transmission unit, a reception unit, a transmission port, and a reception port, the switching unit being set in a first state in which the transmission unit and the transmission port are connected and the reception unit and the reception port are connected or a second state in which the transmission unit and the reception port are connected and the reception unit and the transmission port are connected; a monitoring unit configured to monitor a light level of light input from the reception port or the transmission port; and a control unit configured to set the switching unit in the first state or the second state based on the light level monitored by the monitoring unit.

Abstract: A connector that connects a first multi-core optical fiber to which a first plug is provided and a second multi-core optical fiber to which a second plug is provided to one another, includes: a first jack for inserting the first plug; and a second jack for inserting the second plug, wherein the first jack is configured so that the first plug in a first state and the first plug in a second state can at least be inserted thereinto, and the first plug in the second state is obtained by rotating the first plug in the first state by 180 degrees about an insertion direction as the axis of rotation, the insertion direction being the direction in which the first plug is inserted into the first jack.

Abstract: A communication device includes: a switching unit connected to a transmission unit, a reception unit, a transmission port, and a reception port, the switching unit being set in a first state in which the transmission unit and the transmission port are connected and the reception unit and the reception port are connected or a second state in which the transmission unit and the reception port are connected and the reception unit and the transmission port are connected; a monitoring unit configured to monitor a light level of light input from the reception port or the transmission port; and a control unit configured to set the switching unit in the first state or the second state based on the light level monitored by the monitoring unit.

Abstract: A link connectivity verification message to recognize a physical link connection state is transmitted from the WDM to the PXC on a C-plane. The PXC transmits a link connectivity verification ACK message including information representing a physical link connection state, and the WDM transmits a cross-connect instruction message to cross-connect a transmission side and a reception side of a port (port 1) of the PXC. Probe light transmitted from the port (port a) of the WDM is turned back by a cross-connect of the port (port 1) of the PXC. The WDM receives the probe light to verify a link connectivity.

Abstract: A link connectivity verification message to recognize a physical link connection state is transmitted from the WDM to the PXC on a C-plane. The PXC transmits a link connectivity verification ACK message including information representing a physical link connection state, and the WDM transmits a cross-connect instruction message to cross-connect a transmission side and a reception side of a port (port 1) of the PXC. Probe light transmitted from the port (port a) of the WDM is turned back by a cross-connect of the port (port 1) of the PXC. The WDM receives the probe light to verify a link connectivity.