Time Sensitive Networking – TSN overview

What is TSN?

Time Sensitive Networking or “TSN” refers to a set of IEEE 802 standards that make Ethernet deterministic by default. It has evolved from the industry’s use of Audio / Video bridging (A/V) and the need for more devices and synchronized communications. As more users connect up their devices to the Industrial Internet of Things and Industry 4.0 this also boosts the demand. There are more devices on the networks than ever before and more information being shared and analyzed. Therefore it makes sense that Ethernet has to perform better.

How does Ethernet work today?

Up to now standard Ethernet has worked in an unsynchronized fashion where any device can randomly transmit whenever it wants so the timing is not accurate and is not deterministic. To add to this,  if the Ethernet network load (bandwidth) from broadcasts or other types of communication gets too high this can cause network drops or more delays. With Ethernet, each device operates independently and on their own local clock making sending data in a precise time frame difficult. It should be pointed out here that PROFINET (IRT) already solved these issues since 2004 with PROFINET ASICs.

Determinism with TSN

The advantage of the TSN standards, once completed, is that all standard networking hardware (Intel, TI, Broadcom, PROFINET controllers / devices, others) and switch manufacturers will support the technology just like they do with the Ethernet of today, thus giving us the ability to do deterministic real time control using standard Ethernet hardware with built in TSN support. The network will then use time synchronization and all devices, even network components will operate off the same clock.  This will make it possible to define queues based on time and have a maximum latency which is guaranteed. Of course TSN is only part of a solution as it only makes changes to Layer 2 (data link layer) Ethernet. Coupled with an application protocol like PROFINET we can see big benefits for applications using PROFINET and TSN together.