The combination of two physical layer standards, Ethernet and WiFi, is almost the default in home and enterprise broadband LANs, usually with the wireline technology acting as the backbone. Now the Ethernet standard is diversifying as many other markets, including industrial and automotive, move towards connecting all kinds of devices to one another and the internet, over IP. WiFi may not always be the wireless element – many of these internet of things (IoT) applications will use shorter range standards like Bluetooth Low Energy (BLE) – but Ethernet is being evolved to take a backbone role in cars and factories.
Driven by chipmakers such as Broadcom, technology giants like IBM, and industrial power players like GE, Ethernet is well placed to provide a unifying physical layer and replace many proprietary systems as the IoT spreads its tentacles.
There are now about 30 variants of the Ethernet standard, a significant journey from the first standards-based flavor, which supported 10Mbps in the early 1980s. A collection of standards called Fast Ethernet emerged from the mid-1990s, and today Gigabit and 10Gig Ethernet platforms are common. Even more speed variations are now under development, including 100 GbE and intermediate versions like 25 GbE. Its reach has broadened considerably over the years, from LANs to most of the world’s wide area networks, as well as storage area networks, video delivery systems and so on.
The next target will be the IoT, where Ethernet’s ubiquity will make it the logical candidate to replace proprietary systems and link huge numbers of objects or WPANs to the cloud. However, it has had to acquire new capabilities which were not part of its original remit, but which are seen in specialized M2M and industrial backbones, notably deterministic service delivery, ultra-accurate timing and synchronization, and security.
This process is still ongoing, but much progress has been made by the Carrier Ethernet activities of the Metro Ethernet Forum, founded in 2001 to bring the above qualities to the enterprise focused standard and extend it into telecoms and cloud services. Carrier Ethernet 2.0 was defined in 2012, improving interconnectivity and manageability. Also, precise timing and sync has been addressed, initially for LTE backhaul applications, with the IEEE 1588 Precision Timing Protocol (PTP). For security, the most common protocol in use is IPsec, which works at Layer 3, but a Layer 2 alternative consists of IEEE 802.1AE ‘MACsec’ and its companion key management protocol 802.1af or ‘KeySec’.
These core capabilities, developed for carrier and mobile needs, help to stand Ethernet in good stead for the IoT too, but it can also borrow from other areas of activity, according to the AVnu Alliance, which was formed to support Ethernet as the backbone for professional audio/video data distribution via the IEEE’s AVB (audio video bridging) spec.
Professional AV is an application which typifies the IoT requirements for low latency, deterministic and time-critical connectivity, and so the AVnu work on AVB interoperability can logically be applied to other sectors. The Alliance aims to do just that by extending its work to the emerging TSN (time sensitive networking) extension of Ethernet AVB, which targets industrial and automotive applications and is being driven by the rise of IoT services in these field.
The new focus has seen unfamiliar faces join the AVnu Alliance, including GE, predictably enough considering the influence of its Industrial Internet initiative and its own IoT activities. Also joining are Belden and National Instruments, while other existing members already had interests which spanned multiple sectors, including Broadcom, Cisco, Intel and Xilinx.
TSN is the latest Ethernet extension and is particularly geared to very low latency, targeting worst-case delays of less than 4microseconds per hop at 1Gbps speeds for short messages. It also aims to improve robustness by providing instant switchover to alternative paths and clock paths, in the event of delay or failure, as well as seamless redundancy using multiple simultaneous streams. There is also work, within the same IEEE effort, to reduce the network overhead of configuration and bandwidth reservation.
“For the industrial IoT to work, we need a set of standards everyone can conform to and get the data flowing,” Dan Sexton, project leader at GE Global Research, told EETimes. “Ethernet has tended to be a rallying point for industrial systems, but there have been concerns over a lack of determinism. The goal of TSN is to resolve the problems and create an even stronger rallying point.” TSN itself draws on work by seven IEEE 802 standards sub-groups, and the combined work is about one year from ratification, although chip suppliers are likely to start preparing products far earlier than that, once the specs looks stable.
“There is enough coalescence that we can start as vendors and consumers to think about how to create certifications, do interoperability testing, and the like, so we’re ready when the standards are ratified,” said Paul Didier, IoT architect at Cisco and AVnu Alliance delegate.
Expertise in Ethernet, and combining Ethernet with wireless local networks, will thus be an asset in a growing variety of markets in which the IoT is important. Some of Broadcom’s announcements at CES exemplified this, particularly in the automotive space, where the company showed off an Ethernet physical layer transceiver IC.
The firm aims to harness its Ethernet strengths to take the lead in turning the technology into the default in-car backbone, especially as automotive systems move beyond infotainment to safety and eventually driverless applications. As well as developing chips and lobbying for the cost and security advantages of integrating Ethernet into the auto, Broadcom is also a leading light in the development of BroadR-Reach, an Ethernet physical layer standard specifically for low power automotive connectivity. This week saw the chip vendor unveiling its latest BroadR-Reach chip, along with an NFC chip to enable users to set up mobile devices inside cars with a simple ‘tap-to-connect’ procedure.
Broadcom says that, as infotainment and ADAS (advanced driver assist systems) involve ever-larger quantities of data, Ethernet is gaining ground in cars because of its low cost, interoperability and security. Its new transceiver chip, the BCM89811, promises 100Mbps speeds over a single, unshielded twisted pair wire, making it powerful enough for emerging uses like instrumentation clusters and LTE support. The chip integrates a large number of components on one chip, including low-pass filters, and so comes at a reduced size (6x6mm) compared to its predecessors, and 30% lower power consumption.
Broadcom argues that many different in-car networks are emerging, and many vehicles will feature several of them, and so need an internal backbone to bridge the various domains. Those domains might include a low bandwidth local interconnect network (LIN), a controller area network, a media oriented systems transport (MOST) for transmitting content, and a point-to-point low-voltage differential signaling (LVDS) system for information and safety apps. It will be important for carmakers to be able to separate safety critical subnets from open media ones, but security features in automotive Ethernet do allow different domains to be segregated in a virtualized way. And Ethernet could start to replace some car-specific networks, such as FlexRay, by offering similar speeds at lower costs to OEMs.