IEEE 802.1 TSN and Industrial Ethernet Network Interoperability

By Chantal Polsonetti

Industrial Ethernet (IE) customers are well aware of the numerous non-interoperable implementations that currently exist within the industrial automation realm.  Efforts to bring IE networks in line with industrial requirements have led to network-specific implementations throughout the stack.  These range from physical layer alterations for motion control applications to removal and replacement of TCP/IP at the network layer and/or implementation of differing application layers such as PROFINET and EtherNet/IP.

IEEE 802.1 TSN (Time Sensitive Network) standardization activities are currently of great interest in industrial automation.  TSN offers the prospect for delivering standard, unmodified real-time industrial Ethernet (IE) that overcomes legacy drawbacks in areas such as latency, fault tolerance, scalability, and determinism.  Availability of standard industrial network technology managed as part of the overall IEEE 802.1 Ethernet development work further promises numerous advantages.  These include in areas such as standard silicon, multi-vendor support, lower costs, and eliminating the need for vendor or network-specific real-time implementations.  But concerns about interoperability in industrial applications remain.

IEEE 802.1 TSN, which covers layers 1 and 2 of the network stack, is composed of numerous component standards. Standardization of several components remains incomplete, but IEEE 802.1AS (Timing and Synchronization for Time-Sensitive Applications – one of the profiles within the existing IEEE 1588 Precision Time Protocol (PTP)) and IEEE 802.1Qbv (Time-Aware Scheduling) have been ratified.  With these important components solidified, we anticipate availability of silicon and ultimately initial end products (such as IE switches), that support these and possibly other elements of the emerging standard by the end of this year.

While TSN holds the promise to provide tremendous value in real-time industrial applications, the combination of a multi-component standard in various stages of completion leads to the prospect for differing physical layer implementations.  Similarly, TSN’s focus on layers 1 and 2 does not address continued use of competing industrial application layers in IE-based automation architectures.  Both of these characteristics ultimately contribute to the potential of a continued lack of multi-vendor interoperability in industrial Ethernet applications.

Industry efforts are under way to address interoperability concerns at both the physical and application layers, but these activities are taking place outside of IEEE standardization.  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.  As always, the issue for potential adopters is whether or not your lead automation suppliers participate in and support these activities.

Material for this blog was drawn from ARC’s just-released Industrial Ethernet Switches Global Market Research Study, which includes forecasts for TSN shipments in units, revenues, and by average selling priceFurther information is available at:  www.arcweb.com/market-studies/industrial-ethernet-switches

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