TSN: Network Enabler

Why the Industrial IoT sees Time-Sensitive Networking’s value

Only six months in, 2018 has proven to be a breakthrough year for the expansion of the Industrial Internet of Things (IIoT). And, as it continues to grow, the IIoT represents some of the biggest opportunities for manufacturers and other key stakeholders in factory automation and other industrial markets and applications. A 2017 McKinsey & Company study stated that “the potential value that could be unlocked with IoT applications in factory settings could be as much as $3.7 trillion in 2025, or about one third of all estimated potential economic value.” The new capabilities and opportunity found in industrial settings demand streamlined operational and manufacturing models.

Network infrastructure improvements are a key step in the development of solutions that can optimize systems and operational management models, while helping bring their companies to the forefront of this growth. The need for interoperability, efficiency, and determinism on the network increases as new automation capabilities arise. Enter: Ethernet-based Time Sensitive Networking, TSN.

Understanding Time-Sensitive Networking’s Evolution
Since its inception in the 1970s, Ethernet has morphed from a CSMA/CD technology, where hubs were used for connecting multiple segments together. Over the years, hubs have given way to switches, and collision detection methods have migrated to switching algorithms. These switches and algorithms weren’t traditionally deterministic. Further complicating configuration, all the functionality from 40 years of Ethernet was retained and aggregated into each switch. In the last 20 years, Ethernet has evolved to enable next generation control systems.

To better understand the evolution of TSN, one needs to look back to the late ‘90s through the early 00s when real-time Ethernet and the efforts to build a common foundation were not prioritized. Industry was creating its own unique approaches, with network protocols all competing for adoption. Protocols such as Profinet, Ethernet/IP, Ethernet Powerlink, EtherCAT, Modbus-IDA, and SERCOS III fell short on offering true flexibility and interoperability, serving only individual solutions and applications on the network. Members of the IEEE 802.1 Time-Sensitive Networking task group assembled to address this issue in the late 00s, initially developing the Audio Video Bridging (AVB) standards and later expanding into TSN standards. Changing the name to Time-Sensitive Networking more closely represented a new scope and capabilities in industrial and automotive settings.

Work by IEEE 802, the Internet Engineering Task Force (IETF), and other standards groups has extended the ability to operate time-sensitive systems over standard Ethernet networks, supporting diverse applications and markets including professional audio/video, automotive, and industrial. These standards define new mechanisms for creating distributed, synchronized, real-time systems using standard Ethernet technologies that allow the convergence of low latency control traffic and standard Ethernet traffic on the same network.

Figure 1: Converged TSN Ecosystems and the role Avnu Alliance plays

TSN: A More Capable Ethernet
The updates to standard Ethernet with TSN offer a variety of benefits and differentiators, including:

  • Bounded, low latency data transfer for control
  • Shared synchronized time
  • High bandwidth
  • Convergence of control and standard Ethernet traffic
  • Security enhancements aligned with IT standards.

TSN supports real-time control and synchronization, for example, between motion applications and robots over a single Ethernet network. TSN can, at the same time, support other common traffic found in manufacturing applications, driving convergence between IT and operational technologies. TSN brings a holistic approach to network management, requiring new tools that enable offline modeling of the network traffic and simulation of loading prior to acquisition of hardware or commissioning in the field. Scheduling becomes more calculable from a mathematical perspective by allowing system designers to predict if the network will be successful.

The benefits of TSN include changes to the workflow for designing and planning networks, where it values network calculus and planning for managing traffic and guaranteeing performance. In this new paradigm, payload, sampling frequency, and maximum latency can all be managed from a system-wide view to calculate flows and configure bridges and infrastructure to meet these demands. If designs prove inadequate, or a solution is not achievable given system constraints, then the network design can be modified to accommodate the system requirements.

As TSN-supported network infrastructure becomes more prevalent, many of today’s modified Ethernet networks can move to TSN based networks, using their OT-based application layers on standard 802.1 Ethernet. TSN also fills an important gap in standard networking quality of service, namely guaranteed latency and delivery for critical traffic. Automation and control applications require consistent delivery of data from sensors to controllers and actuators in highly dependable and precise time intervals. TSN ensures that specific traffic is delivered in a timely manner by securing bandwidth and time in the network infrastructure for that purpose while supporting all other forms of traffic. This enables users and vendors to converge networks and derive benefits from the increased connectivity to more and more devices.

By simplifying convergence and increased connectivity while unlocking the critical data needed to achieve improved operations driven by big data analytics, TSN makes the case for its IIoT business value. Designers can take advantage of the advancements in processing, communications, software, and system design with a standard that evolves while providing precise timing.

Driving TSN Adoption
One group driving adoption and the ecosystem is Avnu Alliance. Avnu Alliance fosters and develops an ecosystem of manufacturers providing interoperable devices for pro AV, consumer, automotive, and industrial networked systems. The industrial segment within Avnu includes member companies across the entire ecosystem and supply chain, including network infrastructure vendors, silicon providers, and industrial suppliers, who all work together to create an ecosystem of interoperable low-latency, time-synchronized, highly reliable networked devices built on TSN base standards.

To promote the shared network and accelerate products to market, Avnu Alliance facilitates a common technical platform through various services, including open-source software, hardware reference designs, test plans, and third-party certification to develop and verify the correct operation and implementation of TSN-enabled products.

Avnu Alliance has built a rich set of conformance and interoperability tests with a defined procedure for certification in various markets. Leveraging that multi-industry experience, Avnu defined a baseline certification with robust and comprehensive tests based on the market requirements for industrial automation devices and silicon. These conformance tests ensure that the device or silicon conforms to the relevant IEEE standards, as well as additional requirements that Avnu has selected as necessary for proper system interoperability.

Avnu is committed to accelerating the path to an interoperable foundation. Avnu’s conformance test tools, testbeds, open-source code, and certification program support vendors with rapid adoption of the TSN standards. With Avnu’s initiatives in play for TSN, system designers and engineers will no longer architect a network that becomes outdated before it’s even installed. As the need for time-synchronized communications continues to grow, Avnu Alliance will work to ensure that more companies are able to benefit from TSN’s advantages with successful implementations in industrial settings and beyond.

IIoT promises a world of smarter, hyper-connected devices and infrastructure where manufacturing machines, transportation systems, and the electrical grid will be outfitted with embedded sensing, processing, control, and analysis capabilities. Once networked together, they’ll create a smart system of systems that shares data between devices, across the enterprise, and in the cloud. Facilitating a community of industry leaders that are actively pursuing standardization recognizes that deterministic networking is going to be critical for the industrial environment .

To learn more about Avnu Alliance and upcoming event participation and activities, visit www.avnu.org.

Tom Weingartner is the Marketing Director for the Deterministic Ethernet Technology Group at Analog Devices and has 30 years experience with semiconductors and embedded systems ranging from ASIC design to avionics system development. Weingartner is responsible for ADI’s deterministic Ethernet product line including Industrial Ethernet and Time Sensitive Networking standards.


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