Introduction to the physical layer and data link layer of DoIP system

The physical media connection of the DoIP system's in-vehicle Ethernet can use a combination of a connection that complies with IEEE 802.3 100BASE-TX and an activation line. The Ethernet diagnostic interface can use an RJ45 connector, and its cable specifications are required to be above Category 5. As an in-vehicle node that is directly connected to external test equipment, the DoIP edge node needs to support the detection of physical connection on and off, and notify the communication layer of relevant time information. It must support the 100BASE-TX standard specified in IEEE 802.3 while also supporting the 10BASE-T standard 10Mbit/s connection. It is intended as an alternative solution in an environment where a 100Mbit/s connection cannot be established between two Ethernet interfaces. In this case, the connection can still be established at a lower speed.