DoIP vs. UDS Protocol
Comparing 2 standards across 13 specifications. 13 key differences identified.
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.
Unified Diagnostic Services (UDS, standardized under ISO 14229) is the international application-layer diagnostic communication protocol used across nearly all modern automotive electronic control units (ECUs). Defining standardized diagnostic request/response service IDs (SIDs) for reading Diagnostic Trouble Codes (DTCs), reading real-time live sensor parameters, running actuator self-tests, and cryptographic ECU security access.
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
ISO 13400-2:2019 (Transport protocol and network layer services) | ISO 14229-1 (UDS Application Layer) / ISO 14229-2 (Session Management) |
|
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) | — |
|
Diagnostic Session Control (SID 0x10)
|
— | 0x01: Default Session | 0x02: Programming Session (Flashing) | 0x03: Extended Diagnostic Session |
|
Security Access (SID 0x27)
|
— | Challenge-response seed & key cryptographic authentication unlocking protected ECU coding and calibration memory |
|
Read Data By Identifier (SID 0x22)
|
— | Queries 2-byte Data Identifiers (DIDs, e.g. coolant temp, fuel pressure, engine RPM, battery state-of-charge) |
|
Read DTC Information (SID 0x19)
|
— | Reads stored, pending, and permanent 3-byte Diagnostic Trouble Codes with freeze-frame environmental data |
|
Clear Diagnostic Info (SID 0x14)
|
— | Erases stored DTCs, freeze frames, and resets emissions monitor readiness flags |
|
Negative Response Code (NRC 0x7F)
|
— | Standardized error code returned when service is rejected (e.g. 0x33 Security Denied, 0x31 Request Out Of Range) |