IEEE 802.3bw / 802.3bp
Automotive Ethernet
100/1000BASE-T1 — gigabit backbone for ADAS and zonal architectures.
Bitrate
100 Mbit/s, 1 Gbit/s, 10 Gbit/s
Topology
Point-to-point switched, single twisted pair (UTP)
Introduced
2015
Overview
Automotive Ethernet uses single-pair unshielded cabling to deliver IT-class bandwidth in vehicles. Combined with TSN (Time-Sensitive Networking) and SOME/IP, it powers cameras, lidar, infotainment and zonal gateways.
Frame format
| Field | Bits | Description |
|---|---|---|
| Preamble + SFD | 64 | Synchronization |
| Dest MAC | 48 | Destination address |
| Src MAC | 48 | Source address |
| EtherType / VLAN | 16–32 | Protocol + optional 802.1Q tag |
| Payload | 368–12000 | 46–1500 bytes (jumbo up to 9000) |
| FCS | 32 | CRC32 frame check sequence |
Byte structure — request & response
Automotive Ethernet (100/1000BASE-T1) — IEEE 802.3bw/bp
Frame template
[Preamble 7B][SFD 1B][DstMAC 6B][SrcMAC 6B][802.1Q? 4B][EtherType 2B][Payload 46–1500B][FCS 4B]Request
| Off | Size | Field | Value | Description |
|---|---|---|---|---|
| 0–6 | 7 B | Preamble | 55 55 55 55 55 55 55 | Bit synchronisation pattern. |
| 7 | 1 B | SFD | 0xD5 | Start-of-frame delimiter. |
| 8–13 | 6 B | Destination MAC | 00 11 22 33 44 55 | ECU MAC (or multicast). |
| 14–19 | 6 B | Source MAC | AA BB CC DD EE FF | Tester MAC. |
| 20–23 | 4 B (opt) | VLAN tag | 81 00 00 0A | 802.1Q TPID + VID/PCP. |
| 24–25 | 2 B | EtherType | 0x0800 / 0x88B5 | IPv4, AVTP, SOME/IP, etc. |
| 26… | 46–1500 B | Payload | IP/UDP/SOME-IP request | E.g. SOME/IP request 0x1234.0001. |
| tail | 4 B | FCS | CRC-32 | Frame check sequence. |
Response
| Off | Size | Field | Value | Description |
|---|---|---|---|---|
| 8–13 | 6 B | Destination MAC | AA BB CC DD EE FF | Tester MAC (reversed). |
| 14–19 | 6 B | Source MAC | 00 11 22 33 44 55 | ECU MAC. |
| 24–25 | 2 B | EtherType | 0x0800 | Same upper-layer protocol. |
| 26… | var | Payload | SOME/IP response 0x1234.8001 | Method ID OR'd with 0x8000 marks response. |
| tail | 4 B | FCS | CRC-32 | CRC32 over the frame. |
Automotive Ethernet uses single-pair UTP (BroadR-Reach / 1000BASE-T1). Diagnostics ride on UDP/13400 (DoIP); service-oriented calls use SOME/IP over UDP/16030 or TCP.
Use cases
- · Camera/lidar streaming
- · Infotainment backbone
- · OTA updates
- · Zonal gateways
Pros
- High bandwidth
- Standard IT tooling
- TSN for determinism
Cons
- Switching adds cost
- EMC requires careful design
- More complex stack
Request / Response examples
SOME/IP service request
Request
MsgID:0x1234.0001Method:getCameraFrame()Payload:0B
Response
MsgID:0x1234.8001ReturnCode:0x00Payload:1.2MBJPEGframe
Service-oriented call over UDP/16030 carrying a compressed camera frame.