What is TSN?

Time-Sensitive Networking (TSN) is an extension of standard Ethernet, its primary goal being to make standard Ethernet deterministic. It allows technicians to know precisely the exact time it takes for traffic to travel through the network, and the nature of any delays and time-varying variations (jitter) that traffic will experience.

The tolerance for latency and jitter in typical internet applications is far higher than what many industrial processes can tolerate. Because Ethernet initially could not guarantee the timing of events, it was unreliable for many machine applications, and this lack of determinism could lead to quality degradation or even machine damage.

Various open protocols (such as CC-Link IE) have been used to address these issues, and they still provide valuable functionality for industrial applications when combined with TSN. While these protocols provide a deterministic approach to Ethernet for industrial applications, resulting in what is now known as Industrial Ethernet, they still do not offer a good convergence solution. The current trend towards TSN will eventually fill this gap. However, it is important not to forget that TSN is merely a "pipe" for deterministically transmitting data from one place to another. It does not involve higher-level application functions such as security or motion control. Therefore, these protocols are still needed to implement these functions.

Another consideration for TSN networks is bandwidth. Besides determinism, the standards behind TSN allow industrial Ethernet to utilize this typically fixed resource more efficiently. Prioritization features allocate the necessary bandwidth, ensuring all traffic flows smoothly across the network and preventing secondary data from interfering with higher-priority data.

Which standards are involved in TSN?

The IEEE 802.1 Ethernet specification defines how this technology provides deterministic performance and ultimately convergence by implementing features such as time synchronization and traffic prioritization.

IEEE 802.1Qbv allows defining transmission time slots for network traffic queues. This controls when each type of traffic can access the network. In this example, four time slots are divided among eight queues. Within each time slot, the higher-numbered queue has priority.

IEEE 802.1AS – Timing and Synchronization for Time-Sensitive Applications: Time synchronization provides the foundation for determinism because it ensures all devices on the network share the same time awareness. For example, if it is currently 10:00 AM, all devices on the network know this, and their operations are synchronized to the same clock. Therefore, this minimizes the possibility of time drift that could lead to data transmission delays and variations (latency and jitter), thus supporting timely and predictable delivery of critical data traffic.

IEEE 802.1Qbv – Scheduled Traffic Enhancement

How is the TSN Standard Evolving?

Like any technology, the IEEE 802.1 standard that defines TSN is constantly evolving, with existing standards being refined and new standards emerging frequently. Even as standards evolve, the technology itself becomes mature enough to be implemented in projects. Evolving technologies can be considered more valuable – because they continue to evolve, consistently meeting current needs, and are therefore less likely to become obsolete. Therefore, this evolution is positive.

In contrast to this evolution, Ethernet standards have a long track record of backward compatibility. Ethernet technology has been around for approximately forty years, but in many cases, older devices are often compatible with newer ones. TSN is expected to follow this trend as well. Therefore, companies that need to complete projects immediately can incorporate TSN into their projects right away, confident that it is unlikely to become obsolete in a few years. There is no need to wait for TSN to arrive at some uncertain "ready" moment in the future, as that moment is unlikely to come.