What is TSN?

Time-Sensitive Networking

TSN is a set of standards for real-time data transmission in deterministic Ethernet networks. It is a Layer 2 technology enabled by IEEE 802.1Q.

On this page, we'll discuss the benefits and applications of TSN, provide an overview of its standards, and highlight the support capabilities of our engineering team.

What Is TSN or Time-Sensitive Networking?

Most industrial automation networks provide real-time communication via Ethernet on a physical level. They implement data transmission methods and time synchronization to guarantee timing, latency, and jitter stabilization. But there’s a particular limitation to such an approach, as it leads to vendor lock-in and less-than-optimal use of network infrastructure.

At its inception, the initial purpose of the Ethernet standard was not about meeting real-time network requirements. However, in recent years, The TSN Task Group defined TSN or Time-Sensitive Networking Ethernet sub-standards by IEEE 802.1 with the goal of addressing these real-time and deterministic network requirements.

TSN IEEE 802.1Q standards operate at Layer 2 OSI. TSN is not an Internet Protocol standard, but rather one that concerns itself with Ethernet. Routing and forwarding decisions within a time-sensitive network run via the Ethernet header contents and not the IP address.

How Promwad Drives TSN Development

Through close collaboration with Microchip Technology Inc., Promwad’s TSN Ethernet switch solution offers customers a reliable way to strengthen and expand a network infrastructure that’s used for critical and non-critical data transmissions. Clients that utilize TSN-based solutions can converge numerous services over a single physical network.

Why is TSN Applicable to Any Industrial Application and Why Is It Important?

Ethernet frames are not limited to IP and can be used in any environment.

The number of industries that require deterministic communication is countless: automotive and transportation, manufacturing, industrial automation, etc. The primary reason for this flexibility is the high optimization and connectivity levels, which ultimately results in cost reduction.

Our Chip Vendors with TSN Feature

Core TSN Standards

TSN is comprised of a set of standards. Let’s take a quick look at what they are in the following overview.

Timing and Synchronization: IEEE 802.1ASrev, IEEE 1588

All network elements must share the same time concept as outlined in IEEE 802.1ASrev in order to ensure a deterministic network. The timing synchronization protocol outlined in IEEE 802.1ASrev describes the use of multiple grandmaster clocks in high-availability scenarios. IEEE 802.1ASrev is a subset of the IEEE 1588 PTP synchronization protocol.

Scheduling: IEEE 802.1Qbv, IEEE 802.1Qbu / IEEE 802.3br

TSN utilizes the IEEE 802.1Qbv-defined time-aware scheduler. It allows time-slicing on the network in order to be able to serve different types of traffic.

The primary difference between TSN and non-TSN Ethernet frames lies in the transition methodology:

TSN – transits on a schedule,
non-TSN – transits on a best effort basis.

IEEE 802.1Qbu defines frame preemption, which is a method to interrupt the transmission of extended Ethernet frames in favor of high-priority TSN Ethernet frames. As soon as the TSN Ethernet frame is through, the remaining part of the interrupted Ethernet frame can be transmitted. IEEE 802.3br describes frame preemption for the Ethernet MAC component.

Fault Tolerance and Redundancy: IEEE 802.1Qca, IEEE 802.1CB

IEEE 802.1Qca describes the discovery of the network topology. It works by collecting information from nodes. The main goal of this standard is to find redundant paths in the network.

IEEE 802.1CB Frame Replication and Elimination for Reliability (FRER) sends duplicates of each Ethernet frame over multiple paths, which is how it ensures redundancy for real-time control applications that cannot tolerate packet loss. For example, as specified in IEC 62439-3, redundancy protocols such as HSR and PRP are supported.