Abstract: A vehicular communication device is configured to perform communication in accordance with an Ethernet standard, and includes a medium access controller (MAC), a clock monitor, and a return processor. The MAC is configured to execute medium access control. The clock monitor is configured to monitor a clock signal for operating the MAC. The return processer is configured to restart a clock output source that outputs the clock signal, in response to the clock monitor detecting that the clock signal is stopped.

Abstract: A vehicle relay device includes a plurality of communication ports. Each of the plurality of communication ports communicate with a communication device as a node in accordance with an Ethernet standard. A connection permission node that is a node to be connected is predefined for each of the plurality of communication ports. The vehicle relay device does not communicate with an unregistered node that is a node not registered as the connection permission node.

Abstract: A relay device includes a plurality of ports, a medium access control unit, and a relay processing unit. Each of the plurality of ports provides a physical layer. The medium access control unit is connected to the plurality of ports. The medium access control unit receives a communication frame from one port out of the plurality of ports. The medium access control unit transmits the communication frame to another port out of the plurality of ports. The relay processing unit transmits, in cooperation with the medium access control unit and through the medium access control unit, the communication frame received from the medium access control unit to another port that corresponds to destination information included in the communication frame.

Abstract: A vehicle relay device includes a plurality of communication ports. Each of the plurality of communication ports communicate with a communication device as a node in accordance with an Ethernet standard. A connection permission node that is a node to be connected is predefined for each of the plurality of communication ports. The vehicle relay device does not communicate with an unregistered node that is a node not registered as the connection permission node.

Abstract: A relay device includes a plurality of ports, a medium access control unit, and a relay processing unit. Each of the plurality of ports provides a physical layer. The medium access control unit is connected to the plurality of ports. The medium access control unit receives a communication frame from one port out of the plurality of ports. The medium access control unit transmits the communication frame to another port out of the plurality of ports. The relay processing unit transmits, in cooperation with the medium access control unit and through the medium access control unit, the communication frame received from the medium access control unit to another port that corresponds to destination information included in the communication frame.

Abstract: A vehicular communication device is configured to perform communication in accordance with an Ethernet standard, and includes a medium access controller (MAC), a clock monitor, and a return processor. The MAC is configured to execute medium access control. The clock monitor is configured to monitor a clock signal for operating the MAC. The return processer is configured to restart a clock output source that outputs the clock signal, in response to the clock monitor detecting that the clock signal is stopped.

Abstract: An in-vehicle relay device includes a layer 2 relay unit and a layer 3 relay unit. A hardware circuit performs functions of a layer 1 to a layer 3. A microcomputer performs functions of a layer 4 and higher layers than the layer 4.