A communication system has: a monitoring unit 201 monitoring power consumption in a switching unit 20 forwarding a communication message; a power consumption data transmission unit 202 transmitting a data indicating the power consumption monitored by the monitoring unit 201; a control signal receiving unit 203 receiving a control signal; a control unit 204 controlling a data transfer rate on the basis of content of control included in the control signal received by the control signal receiving unit 203; a power consumption data receiving unit 301 receiving the data indicating the power consumption transmitted by the power consumption data transmission unit 202; a control determination unit 302 determining, on the basis of the data received by the power consumption data receiving unit 301, target of control and the content of control regarding power consumption; and a control signal transmission unit 303 transmitting the control signal including the target of control and the content of control determined by the control determination unit 302.