DoIP stands for Diagnostics over Internet Protocol. Defined by the ISO 13400-2 standard, it carries diagnostic communication between external test equipment and a vehicle's electronic control units over IP, using TCP and UDP.
Because it runs over the standard Ethernet physical layer, it is also referred to as Diagnostics over Ethernet.
What Changes for the Workshop
The practical consequence is bandwidth. CAN operates at up to 500 kbps; Ethernet-based DoIP supports up to 100 Mbps.
| CAN | DoIP | |
|---|---|---|
| Speed | Up to 500 kbps | Up to 100 Mbps |
| Topology | Bus structure | Switched — one switch per network node |
| Data volume | Limited | Large transfers practical |
That difference is why modern vehicles use it. Flashing a control unit that would take a very long time over CAN becomes a realistic operation over DoIP, and the standardised data format makes large transfers less error prone.
Remote Diagnostics
Because DoIP provides access to the vehicle's control units over IP, diagnostic data can be retrieved without physical access to the vehicle. In practice DoIP is the gateway that makes remote vehicle diagnostics possible at all, and it also supports communication between the vehicle's onboard and off-board diagnostic systems.
Where It Sits Alongside UDS
Diagnostic services were historically delivered over proprietary protocols or KWP. The industry moved to Unified Diagnostic Services (UDS), which works across CAN, K-line, FlexRay and Ethernet, and UDS is now the standard in general use.
DoIP is not a competitor to UDS — the DoIP transport layer is defined as part of the UDS specification. UDS describes the diagnostic services; DoIP carries them.
What This Means When Buying Equipment
This is the part that matters commercially. A diagnostic tool without DoIP support cannot communicate with a vehicle that requires it, regardless of how good its coverage is otherwise. As DoIP-equipped vehicles reach the general repair market, a tool bought without it dates faster than expected.
The cabling matters too: DoIP uses a lightweight, simply shielded cable rather than the CAN wiring workshops are used to.
When choosing equipment, DoIP support is worth confirming explicitly rather than assuming — it is the difference between a tool that covers newer vehicles and one that does not.
Equipment
See our diagnostic devices range, or tell us which makes and model years you work on and we will confirm which tools include DoIP support.
