A vehicle can use controlled area network (CAN) buses for communications within a subsystem but connect different subsystems using Ethernet connections. For example, a network interface (NIC) of a subsystem can receive a CAN message from a CAN bus and incorporate the CAN message into a user diagram protocol (UDP) message which can be then packaged into an Ethernet packet. The UDP message may include a table of contents (TOC). The TOC may include the message ID and the length of the CAN message. Once a NIC receives the message, the receiving NIC can extract the UDP message from the Ethernet packet, parse through the TOC to identify a CAN message relevant to the control units of the receiving NIC's subsystem, extract the relevant CAN message based on the TOC, and put the CAN message onto CAN buses to be sent to destination CAN devices.