IEEE 802.3 / TCP/IP
Ethernet (TCP/IP)
Standard IP networking for diagnostics, OTA and telematics.
Bitrate
100 Mbit/s – 10 Gbit/s
Topology
Switched star
Introduced
1980
Overview
Classical Ethernet plus TCP/IP underpins DoIP diagnostics, OTA flashing, and connectivity to backend services. Most modern vehicles bridge legacy CAN/LIN traffic onto Ethernet via a central gateway.
Frame format
| Field | Bits | Description |
|---|---|---|
| Ethernet header | 112 | MAC addresses + EtherType |
| IP header | 160 | IPv4/IPv6 header |
| TCP/UDP | 160 / 64 | Transport layer |
| Payload | var | Application data (DoIP, HTTP, MQTT…) |
Byte structure — request & response
Ethernet + TCP/IP
Frame template
[Eth 14B][IP 20B][TCP/UDP 8/20B][App payload]Request
| Off | Size | Field | Value | Description |
|---|---|---|---|---|
| 0–13 | 14 B | Ethernet header | DstMAC SrcMAC EtherType=0x0800 | Layer-2 framing. |
| 14–33 | 20 B | IPv4 header | Src=192.168.1.10 Dst=192.168.1.20 Proto=17 | Source/dest IPs, protocol = 17 (UDP) or 6 (TCP). |
| 34–41 | 8 B | UDP header | SrcPort=49152 DstPort=13400 Len Csum | UDP for DoIP discovery. |
| 42… | var | DoIP payload | 02 FD 00 01 00 00 00 00 | DoIP Vehicle Identification Request (Payload Type 0x0001). |
Response
| Off | Size | Field | Value | Description |
|---|---|---|---|---|
| 0–13 | 14 B | Ethernet | MACs swapped | Reply Layer-2 header. |
| 14–33 | 20 B | IPv4 | Src=192.168.1.20 Dst=192.168.1.10 | Reply IPs swapped. |
| 34–41 | 8 B | UDP header | SrcPort=13400 DstPort=49152 | DoIP server port. |
| 42… | var | DoIP Vehicle Announcement | 02 FD 00 04 00 00 00 21 <VIN><LA><EID><GID><Action> | Payload Type 0x0004 with VIN, logical address, EID, GID, further action byte. |
Diagnostics over IP (DoIP) defines payload types — 0x0001 request, 0x0004 announcement, 0x0005/0x0006 routing activation, 0x8001 diagnostic message tunnelling UDS bytes.
Use cases
- · DoIP diagnostics
- · OTA updates
- · Telematics
- · Workshop tooling
Pros
- Universal tooling
- Huge bandwidth
- Internet integration
Cons
- Not deterministic without TSN
- Heavy stack for small ECUs
Request / Response examples
DoIP vehicle announcement
Request
UDP/13400Payload:0x0004(VehicleIdentificationRequest)
Response
Payload:VIN+LogicalAddress+EID+GID
Tester discovers vehicles on the workshop network before opening a TCP session.