DoIP
Diagnostics & Protocols · 7 specs
Direct Answer
Diagnostics over Internet Protocol (DoIP, standardized under ISO 13400) replaces slow serial buses with high-speed Automotive Ethernet (100BASE-TX, 100BASE-T1, 1000BASE-T1) using standard TCP/IP and UDP protocols. Operating over TCP Port 13400, it accelerates ECU firmware reflashing and over-the-air (OTA) software updates by up to 100× compared to legacy CAN bus.
Source: ISO 13400-1 / ISO 13400-2:2019 (Road vehicles — Diagnostic communication over Internet Protocol) · Last reviewed Aug 28, 2026
Specs
| Standardization | ISO 13400-2:2019 (Transport protocol and network layer services) |
| Physical Layer | 100BASE-TX (Standard twisted-pair Ethernet) or 100BASE-T1 / 1000BASE-T1 (Single-pair Automotive Ethernet) |
| Network Port | TCP Port 13400 (Diagnostic message transport) & UDP Port 13400 (Vehicle discovery and routing activation) |
| OBD-II DLC Activation Pin | Pin 8 on OBD port is driven to +12V or pulled down to wake up the vehicle's DoIP Ethernet gateway |
| Throughput Advantage | 100 Mbps to 1 Gbps throughput, roughly two to three orders of magnitude faster than 500 kbps CAN bus for large ECU firmware transfers |
| Vehicle Identification Handshake | Vehicle Announcement Message broadcasts VIN (17 chars), Logical Address (2 bytes), and MAC address via UDP broadcast |
| OEM Deployments | BMW (ENET cable / ISTA), Mercedes-Benz (Xentry DoIP), Volvo (VIDA), Porsche, modern VAG platform (ODIS) |
The BMW ENET Cable Architecture
Modern BMW vehicles integrate native DoIP Ethernet directly into the OBD-II port. A BMW ENET cable is an aftermarket/OEM-diagnostic cable that wires an RJ-45 Ethernet plug to the manufacturer-specific Ethernet pins BMW routes onto the OBD-II connector (commonly documented as pin 8 for activation, with the TX/RX pairs on other discretionary pins — consult BMW's own pinout documentation for a specific chassis before building a cable, since exact pin assignments have varied across model generations).
Connecting a laptop directly to the OBD port assigns a local 169.254.x.x IP via link-local addressing (IPv4 APIPA), establishing a direct 100 Mbps TCP stream into the central vehicle gateway.