CAN FD vs. DoIP
Comparing 2 standards across 12 specifications. 12 key differences identified.
CAN FD (Controller Area Network with Flexible Data-Rate, developed by Bosch in 2012 and standardized under ISO 11898-1:2015) extends classical CAN bus to overcome bandwidth bottlenecks in modern vehicles. Increasing payload size from 8 bytes to 64 bytes and accelerating data transmission during the data phase from 500 kbps up to 2, 5, or 8 Mbps.
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
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
ISO 11898-1:2015 (Standardized CAN FD) | ISO 13400-2:2019 (Transport protocol and network layer services) |
|
Data Payload Capacity
|
Expanded from 8 bytes (Classic CAN) up to 64 bytes per frame (eightfold increase) | — |
|
Dual Bit-Rate Architecture
|
Arbitration Phase: 500 kbps (preserves long wire distance and arbitration) | Data Phase: Switched to 2 Mbps, 5 Mbps, or 8 Mbps | — |
|
Bit Rate Switch (BRS) Bit
|
Single control bit in header switches transceiver clock into high-speed mode and back after CRC | — |
|
CRC Integrity Protection
|
17-bit CRC for payloads up to 16 bytes; 21-bit CRC for payloads up to 64 bytes (with 4-bit stuff-count field) | — |
|
Modern Vehicle Deployments
|
Mandatory in modern ADAS radar/camera fusion, encrypted gateway security, and EV battery management systems (BMS) | — |
|
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) |