Abstract: A control module includes a first power-supply-signal connection portion for connection of a power supply signal with one adjacent control module and a second power-supply-signal connection portion for connection of the power supply signal with the other adjacent control module. In the same control module, the first power-supply-signal connection portion, the second power-supply-signal connection portion, and a power input portion in a monitoring-and-control processing unit are connected to each other.

Abstract: Ring type switches 10X, 10Y that connect to two sub-rings 51, 52 are provided to maintain Ethernet communications between sub-rings even when a fault occurs in a ring type switch. By carrying out redundant control processing based on the operating status of itself and the companion in these ring type switches 10X, 10Y, one operates as the currently used system and carries out relay connections between the sub-rings 51, 52 and the other operates as a standby system and stops relay connections between the sub-rings 51, 52.

Abstract: If either of the MAC processing units in one of the ring connection control circuits receives a MAC frame that includes control information for the redundancy control process related to one of the subrings from that subring, then output of the relevant MAC frame to the transfer processing unit is restricted and the relevant MAC frame is output to the STP processing unit.

Abstract: A connector unit includes a communication line connecting a receiving port of a physical layer unit of a node to one adjacent node, and a communication line connecting a transmitting port of the physical layer unit to the one adjacent node via a capacitor, and a connector unit includes a communication line for connecting a receiving port of a physical layer unit of the node to the other adjacent node, and a communication line for connecting a transmitting port of the physical layer unit to the other adjacent node via a capacitor, wherein the connector unit is connected to a connector unit of the one adjacent node, so that the communication line of the node is connected to the communication line of the one adjacent node, and the communication line of the node is connected to the communication line of the one adjacent node.

Abstract: Ring type switches 10X, 10Y that connect to two sub-rings 51, 52 are provided to maintain Ethernet communications between sub-rings even when a fault occurs in a ring type switch. By carrying out redundant control processing based on the operating status of itself and the companion in these ring type switches 10X, 10Y, one operates as the currently used system and carries out relay connections between the sub-rings 51, 52 and the other operates as a standby system and stops relay connections between the sub-rings 51, 52.

Abstract: If either of the MAC processing units in one of the ring connection control circuits receives a MAC frame that includes control information for the redundancy control process related to one of the subrings from that subring, then output of the relevant MAC frame to the transfer processing unit is restricted and the relevant MAC frame is output to the STP processing unit.