In-vehicle communication device and vehicle communication method

An in-vehicle communication device for transmitting and receiving a signal by a predetermined communication protocol related to Ethernet®, the in-vehicle communication device comprising:

• a control circuit configured to generate transmission data including at least two Ethernet frames and interrupt data inserted into an inter-frame gap between the at least two Ethernet frames, the inter-frame gap being a gap between a transmission of the at least two Ethernet frames;
• and
• a PHY unit having a communication circuit configured to convert the transmission data generated by the control circuit into a signal for transmission along a bus and transmit the signal along the bus,
• wherein the interrupt data includes information for managing relay of the Ethernet frames included in the transmission data, and the information includes a priority for determining whether or not to relay the Ethernet frames before another Ethernet frame when relaying the Ethernet frames to another in-vehicle communication device via a relay device.