VEHICLE CONTROL SYSTEM AND COMMUNICATION PROCESSING METHOD

A vehicle control system includes two control device groups respectively constituting two communication networks, a communication management device communicably connected to the two control device groups, and a routing device that routes communication between the two communication networks. When a message is received from one of control devices, the communication management device performs authentication processing for the control device and includes a communication address of one control device as a transmission source address in a relay message for relaying the message received from the one control device to a control device of the other of the control device groups, and the control device of the other of the control device groups performs communication with the one control device by using the communication address of the one control device included in the relay message without interposition of the communication management device.