DoCAN vs. DoIP
Comparing 2 standards across 13 specifications. 13 key differences identified.
Diagnostics on CAN (DoCAN, standardized under ISO 15765-2 and ISO 15765-4) is the network and transport layer protocol that enables diagnostic protocols (such as UDS ISO 14229 and OBD-II ISO 15031) to transmit multi-byte messages (up to 4095 bytes) over 8-byte CAN bus frames. Managing packet segmentation, Flow Control handshakes, and block sizes.
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.
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
ISO 15765-2 (ISO-TP Network Layer) / ISO 15765-4 (Emissions CAN) | ISO 13400-2:2019 (Transport protocol and network layer services) |
|
Maximum Message Length
|
Up to 4,095 bytes (segmented across multiple sequential 8-byte CAN frames) | — |
|
Single Frame (SF–PCI 0x0_)
|
Used when total payload fits in a single frame (up to 7 bytes in Classic CAN; byte 0 indicates data length) | — |
|
First Frame (FF–PCI 0x1_)
|
First frame of a segmented message; bytes 0-1 encode the total 12-bit message length (e.g. 0x10 0x80 = 128 bytes) | — |
|
Flow Control Frame (FC–PCI 0x3_)
|
Receiver sends Flow Status (Clear to Send), Block Size (BS), and Separation Time (STmin) pacing inter-frame delays | — |
|
Consecutive Frame (CF–PCI 0x2_)
|
Transmits remaining data with a 4-bit rolling Sequence Number (0 to 15) to detect dropped packets | — |
|
Emissions OBD Request IDs
|
Standard 11-bit functional broadcast ID: 0x7DF | Standard response IDs: 0x7E8 (Engine ECM), 0x7E9 (TCM) | — |
|
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) |