Did you know that a car has more than a mile of wiring inside and that it’s the third-heaviest system in a car?

Plus, on average, cars in the U.S. are used for about 11-12 years. For every car sold this year, all their cameras, sensors, infotainment systems, electronics, and networking systems must last till at least 2035, no matter where they are driven and how harsh it gets inside or outside.

This extreme test of survival requires cutting-edge optimization and engineering supported by state-of-the-art test instruments and software. In this article, find out how networking innovations like automotive Ethernet are helping to optimize long-term design while also elevating the in-car experience.

What is automotive Ethernet?

Fig 1. Automotive Ethernet with other in-vehicle networks

Automotive Ethernet is a set of protocols and device standards that adapt Ethernet technologies for automotive use, specifically for in-vehicle networking .

The history of automotive Ethernet started with the BroadR-Reach initiative by Broadcom. Since then, all aspects of the technology have been standardized to discourage proprietary implementations and promote interoperability between vehicle, networking, and software systems.

In the sections that follow, we explore the uses of automotive Ethernet, compare it with existing in-vehicle networking technologies, and explore its future.

What is automotive Ethernet used for?

Currently, automotive Ethernet is largely used for applications that need lots of bandwidth (i.e., push high volumes of data on the network every second). Such high-bandwidth applications include:

• Infotainment systems: Transmitting video data from storage media to the head unit requires 5-25 megabits per second (Mbps). Specialized protocols like audio video bridging (AVB), time synchronization, and bandwidth reservation have been designed to take advantage of Ethernet’s strengths for high-quality multimedia features.
• Camera feeds: Advanced driver assistance systems (ADAS) and autonomous driving use cameras for all-around visibility of the vehicle’s surroundings. Each camera sends about 500-3,500Mbps of video frame data. Interestingly, another in-vehicle networking platform, automotive SerDes, is gaining momentum for applications requiring high-definition image transmission, such as rear safety cameras.
• Interconnection backbones: The ever-increasing number of sensors, cameras, and features means a lot of data flows between the electronic control units (ECUs) in charge of various subsystems. Since Ethernet has a symmetric point-to-point rather than a shared bus topology, every pair of nodes on the network can communicate at the designed network bandwidth, like 100 Mbps or higher. The aggregate bandwidth across all connections can go very high in the gigabits-per-second (Gbps) range. Most other automotive networking technologies can’t sustain such high data rates.
• Diagnostics: Automotive Ethernet is particularly suited for transmitting large amounts of diagnostic data that all subsystems produce in modern vehicles.

For more critical automotive applications — like vehicle control, steer by wire, anti-lock braking, or automotive radar sensors — that require real-time responses and fault tolerance, vehicle manufacturers still rely on existing technologies like the controller area network (CAN) and FlexRay because they are more mature, proven in an automotive environment, and cost-effective.

However, recent standards like the Institute of Electrical and Electronics Engineers (IEEE) 802.1AS standard for time-sensitive networking (TSN) enable automotive Ethernet to achieve the low latencies required for such real-time subsystems. For example, many car makers are using it for their vehicles’ digital instruments, data recorders, panoramic ECUs, and AVB switches.

What are the differences between automotive Ethernet and standard Ethernet?

To understand the differences, it helps to first know their similarities. We’ll start with how an Ethernet network relates to the Open Systems Interconnection (OSI) model of network functions.

Fig 2. How Ethernet standards correspond to the OSI model

Ethernet specifications correspond to two logical layers:

• Physical layer: At the bottom is the Ethernet physical (PHY) layer, which concerns itself with low-level physical, electrical, and optical aspects. These include diverse physical media through which the signals propagate, like twisted pairs of wires or optical fibers. They also specify a variety of voltage signaling levels, modulation schemes, connector designs, and other low-level electrical and optical aspects. Dozens of Ethernet PHY implementations exist, just two of which are the 100BASE-TX (for 100 Mbps bandwidth over a twisted pair of wires and specified by the IEEE 802.3u-1995 standard) and the 400GBASE-DR4 (for 400 Gbps bandwidth over single-mode optical fibers).
• Data link layer: At this layer, the Ethernet standards handle the transfer of data frames over whatever PHY implementations exist underneath. They are completely blind to the diversity of PHY implementations. This means a node with a twisted pair PHY and one with a fiber PHY can talk without knowing any details about each other’s physical aspects.

The takeaway here is that diverse PHY implementations exist. Automotive Ethernet is just another set of PHY implementations. All its differences with standard Ethernet are at the PHY level. The layers above remain completely oblivious to these differences, enabling existing networking stacks, operating systems, and software to work with automotive Ethernet just like any other Ethernet.

Here’s how automotive Ethernet is different from standard Ethernet:

• Very different environments and uses: Compared to standard Ethernet in an office or home, a vehicle is an extremely harsh environment with lots of electromagnetic interference (EMI), temperature variations, vibrations, dust, and grime. Additionally, office networks are routinely overhauled every few years, but a vehicle is designed to last for 11-12 years without requiring any overhaul of its internal wiring.
• Different standards: Automotive Ethernet has its own standards, like 100BASE-T1, 1000BASE-T1, and 10BASE-T1S.
• Fewer and shorter wires to reduce weight and cost: Vehicle manufacturers are always looking for ways to reduce the overall weight and improve energy efficiency. Automotive Ethernet uses a single twisted pair of wires designed for shorter distances, while standard Ethernet uses 2-4 pairs of wires. So automotive wiring is between one-fourth to half as heavy, which translates into a few dozen pounds less over the length of the internal wiring.
• Unshielded wires: The two wires form an unshielded twisted pair to further reduce the weight and cost of shielding. To avoid EMI and ensure electromagnetic compatibility (EMC), automotive Ethernet uses differential signaling.
• Full duplex operations: Automotive Ethernet twisted pairs operate with full duplexity (i.e., they can simultaneously transmit and receive). In contrast, for most standard Ethernet variants, except the very latest ones like 10GBase-T, individual pairs work in simplex (one-way) mode. They are effectively full duplex only when we consider all pairs.

What are the standards and protocols associated with automotive Ethernet?

Some of the key standards of automotive Ethernet are:

• IEEE 802.3bw for 100BASE-T1 PHY (100 Mbps over a single twisted pair)
• IEEE 802.3bp for 1000BASE-T1 PHY (1 Gbps over a single twisted pair)
• IEEE 802.3cg for 10BASE-T1S PHY (10 Mbps over a single twisted pair)
• IEEE 802.3ch for 2.5, 5, and 10 Gbps automotive Ethernet PHYs
• IEEE 802.3cy for 25 Gbps PHY
• Detailed specifications for every aspect of automotive Ethernet published by an alliance between the automotive industry and technology providers called One-Pair Ether-Net Alliance Inc. (or OPEN Alliance)
• IEEE 802.1Qav quality-of-service standards for forwarding and queuing in time-sensitive streams
• IEEE 802.1AS for timing and synchronization

How does automotive Ethernet differ from other in-vehicle networks?

In this section, we understand some key differences between automotive Ethernet and other in-vehicle networking technologies like CAN, CAN flexible data rate (CAN FD), and CAN extended data-field length (CAN XL); automotive SerDes; FlexRay; and local interconnect network (LIN).

1. Automotive Ethernet vs. CAN / CAN FD / CAN XL

Fig 3. CAN and Ethernet topologies

The differences include:

• Network topology: CAN has a bus topology. In a subsystem, each node is connected to its two-wire CAN bus through two wires. A vehicle has multiple CANs to handle different subsystems, such as a powertrain CAN. In contrast, automotive Ethernet is a star topology that connects nodes through Ethernet switches, but any pair of nodes can effectively talk like a point-to-point connection. However, 10BASE-T1S offers both a multi-drop bus mode that works like CAN and a point-to-point mode.
• Bandwidth: CAN is limited to around 1 Mbps bandwidth. However, Can FD and the newer CAN XL can achieve 2-10 Mbps. Automotive Ethernet’s 10BASE-T1S also provides 10 Mbps.
• Conflict resolution: Since CAN uses a shared bus, it needs some way to resolve conflicts when two nodes decide to send simultaneously. Automotive Ethernet generally doesn’t need conflict resolution since it’s effectively point-to-point. However, the 10BASE-T1S bus mode implements PHY-level collision avoidance.

2. Automotive Ethernet vs. SerDes

Automotive SerDes is a recent standard proposed by the Automotive SerDes Alliance and is a competitor for mindshare with automotive Ethernet. Their differences include:

• Asymmetric vs. symmetric communication: Automotive Ethernet is symmetric; both downlink and uplink can operate at the same data rates. But that’s a waste of resources in vehicles because downlink throughput from cameras or sensors toward ECUs is very high. At the same time, uplink is much lower, sending just a few control commands periodically. SerDes acknowledges this and optimizes its design for asymmetric operations.
• Bandwidths: Unlike the other network technologies, automotive SerDes is already capable of 16-64Gbps bandwidth, while automotive Ethernet is currently at 10 Gbps.

Automotive SerDes is a common connection for high-resolution in-vehicle displays, such as infotainment or back-up cameras.

3. Automotive Ethernet vs. FlexRay

FlexRay was a popular technology in some high-end vehicles, but most of their manufacturers back SerDes now. Automotive Ethernet’s 10Base-T1S is comparable to FlexRay in bandwidth and fault tolerance.

4. Automotive Ethernet vs. LIN

LIN, specified by the International Organization for Standardization (ISO) via its ISO 17987 standard, remains a simple and popular technology for secondary systems like door and light control. It operates at a few kilobits per second. LIN is unlikely to be replaced any time soon due to its simplicity and cost-effectiveness.

What are the advantages of automotive Ethernet compared to other in-vehicle protocols?

Compared to most of the other protocols (other than SerDes), the advantages of automotive Ethernet are:

• bandwidths that can scale up across a variety of applications
• compatibility with existing networking stacks and software
• no chances of node conflicts due to its design
• endlessly scalable due to its hub-and-spoke topology

What are the disadvantages of automotive Ethernet?

Some current disadvantages are:

• needs more validation by manufacturers since it’s new compared to the older technologies
• higher costs and more weight compared to CAN due to the need for switches

How do you protect automotive Ethernet against cyber threats?

Fig 4. BreakingPoint network security testing software

The open interfaces of connected vehicles make them prime targets for cyber attacks that may even be fatal. Strategies to improve automotive Ethernet cybersecurity include:

• Creating isolated zones: Create virtual local area networks to isolate mission-critical subsystems from others, to prevent snooping, and to avoid privacy violations.
• Deploying a security or gateway ECU: Such devices are dedicated to implementing in-vehicle cybersecurity and supervise critical functions for any subversion.
• Implementing access control: Implement proven office strategies like using firewalls and access control lists to protect vehicle subsystems.
• Setting up intrusion detection: Use the same intrusion detection techniques as used in office networks.
• Mitigating denial-of-service (DoS) attacks: Monitor in-vehicle network traffic and bandwidth usage to identify DoS attacks early and mitigate them by throttling down or dropping suspicious connections.

What are the future trends in automotive Ethernet?

The trends in the automotive industry related to Ethernet developments include:

• Zonal architectures: There’s a shift from networking topologies based on domains (subsystems) to zonal architectures where each zone aggregates information from diverse subsystems around it.
• Convergence of standards: Competing PHY specifications from the OPEN Alliance and the automotive SerDes Alliance may converge as both move toward 100 Gbps bandwidths.
• Software-defined vehicles: Every feature of a vehicle, from its essential driving functions to non-essential infotainment, can be configured and activated over the network.

Rely on O2X Intel for automotive Ethernet verification

In this article, we explained how automotive Ethernet is facilitating high-bandwidth applications in modern vehicles to the point where the industry is starting to think about software-defined vehicles.

Whether you’re a vehicle manufacturer or a network equipment provider, O2X Intel offers comprehensive hardware and software solutions for your automotive Ethernet testing, including:

• test software like IxANVL for automated network protocol validation, IxNetwork VE for L2-L3 testing of virtual network infrastructure and devices, and IxLoad for L4-7 performance testing of multiplay services, application delivery platforms, and network security appliances
• BreakingPoint test software for automotive network security testing
• standards compliance testing, including transmitter and receiver testing according to OPEN Alliance specifications, protocol trigger and decode for IEEE 802.3bw and 802.3bp compliance, and channel testing for OPEN Alliance specifications