Automotive Ethernet Overview

Benefits to using Automotive Ethernet include faster data communication for in-vehicle networking; cost-saving, lighter weight cabling; and software interfaces for upper layers of the Ethernet stack that are the same as those utilized for standard Ethernet.

The Ethernet protocol enables an open technology, high bandwidth network for in-vehicle communication and improves the ability to share data from a common source to an entire network. One critical element of Ethernet is the Ethernet frame (also known as an Ethernet packet), which includes such data as destination MAC address, source MAC address, 802.1Q header (optional), EtherType or length of frame, payload, and a Cyclic Redundancy Check (CRC) called the Frame Check Sequence (FCS). A minimum inter-frame gap of 12 bytes must follow the termination of the Ethernet frame or packet.

IEEE 802 is a family of IEEE standards related to the Data Link and Physical (PHY) layers of the Open Systems Interconnection (OSI) network communication model. The IEEE 802 standards are specific to networks that transport variable-size packets. Within this family are the IEEE 802.1 standards that provide specifications for local area network (LAN), metropolitan area network (MAN), and bridging architecture and network management. Also in this family are the IEEE 802.3 standards, which define the physical layer (PHY) and the media access control (MAC) of the data link layer of wired Ethernet.

The Ethernet standard as it applies to in-vehicle networking is especially influenced by the following specifications:

IEEE 802.1AS-2011—Specifies the protocol and procedures used to ensure time synchronization for time sensitive applications, such as audio and video, over a virtual bridged local area network.

IEEE 802.1Q-2018—Specifies how MAC service is supported by bridged networks, principles of operation, and the operation of MAC and VLAN bridges, including management, protocols, and algorithms.

IEEE 802.3bw—100BASE-T1 Physical Layer (PHY) specifications and management parameters for full duplex 100 Mb/s communication over single twisted pair cabling.

IEEE 802.3bp—1000BASE-T1 Physical Layer (PHY) specifications and management parameters for full duplex 1 Gb/s communication over single twisted pair cabling.

IEEE 802.3Qav—Specification governing audio video bridging.

IEEE 1722-2016—Transport protocol standard for time-sensitive applications on bridged local area networks. This standard enables interoperable audio and video streaming by defining raw and compressed audio/video formats, synchronization mechanisms, and address assignments.

PDF versions of the IEEE 802 standards are available on the Institute of Electrical and Electronics Engineers (IEEE) website, ieee.org.