IEEE approves TSN standard

The ARC Advisory Group has announced that on 19 June the Institute of Electrical and Electronics Engineers (IEEE) published the 802.1AS-2020 standard for time-sensitive networks (TSN).

TSN and the associated joint IEC/IEEE 60802 TSN Profile for Industrial Automation offer the prospect for delivering standard, unmodified real-time industrial Ethernet (IE) that meets the requirements for industrial automation while overcoming legacy drawbacks in areas such as latency, fault tolerance, scalability and determinism.

This important component of the Ethernet TSN standard was deemed necessary since current IEEE 802 technologies for time-sensitive applications, such as high-quality audio/video streaming or industrial control, do not assure that the applications can present data with acceptable jitter, wander and time deviation. Prior solutions, such as IEEE 1588-2002, operate at layer 3 and can represent significant cost and complexity.

The new IEEE 802.1AS-2020 standard (802.1AS-2020 - IEEE Standard for Local and Metropolitan Area Networks--Timing and Synchronization for Time-Sensitive Applications) is designed to operate at layers 1 and 2, making it easier for networked devices to meet these requirements across a variety of time-sensitive applications, including multiple data streams delivered to multiple endpoints. Availability of the standard scheduling component will help alleviate the potential for differing physical layer implementations across vendor offerings.

The standard encompasses maintenance of synchronised time during normal operation as well as addition, removal or failure of network components and/or reconfiguration. The published standard also now specifies the synchronisation of managed objects as part of hot standby as well as protocols and procedures to ensure timing requirements are met in audio, video, control and other time-sensitive network activities.

Availability of standard industrial network technology managed as part of the overall IEEE 802.1 Ethernet development work promises numerous advantages to industrial technology users. These include standard, less expensive and more widely available silicon, multi-vendor support, lower costs and eliminating the need for vendor or network-specific real-time implementations. Scheduling and other components of TSN can still be complex to implement, however, and require use of managed switches.

TSN’s focus on layers 1 and 2 does not address continued use of competing industrial application layers in Ethernet-based automation architectures. Industry efforts are underway to address application layer interoperability, but these activities are taking place outside of IEEE. Examples include the interoperability efforts of the AVNU Alliance and the TSN Testbed activity within the Industrial Internet Consortium, as well as the push to make OPC UA over TSN the universal means for communicating between industrial controllers and the cloud.

Image: ©stock.adobe.com/au/bas121