As described above, in the communication system 1a according to the present embodiment, processing signals transmitted from the functional units (in the case of the PON interface 10a, the software unit 101) are first collected to the signal sorting unit 250 included in the nearby device 20a-1. When transmitting the processing signals to another functional unit, the functional units add destination information to the processing signals. Then, the functional units emit the processing signals from prescribed communication ports. Thus, the processing signals are sent to the signal sorting unit 250 of the nearby device 20a-1.

Upon acquiring each processing signal, the signal sorting unit 250 identifies a functional unit to which the processing signal is to be transmitted, by referring to destination information added to the processing signal. Then, the signal sorting unit 250 transmits the processing signal via a communication port that is connected to a device that includes the functional unit to which the processing signal is to be transmitted. Thus, the processing signal is sent to the functional unit to which the processing signal is to be transmitted. Note that if the functional unit to which the processing signal is to be transmitted is included in the device (i.e., the nearby device 20a-1) that includes the signal sorting unit, the signal sorting unit 250 transmits the processing signal directly to the functional unit, not via a communication port.