New-TechEurope Magazine | November 2017 | Digital Edition

Figure 1 . Automation Pyramid with typical assignment of networks to hierarchies.

This convergence is providedbyTime Sensitive Networking (TSN). TSN is a set of IEEE 802 sub-standards which, when implemented, enable deterministic communication over Ethernet networks while keeping the benefits of communication in best effort manner, on that same network. TSN introduces different traffic classes that share the same link. TSN network configuration reserves resources for streams with deterministic time characteristics. TSN, therefore, enables one common network to be implemented which supports multiple communication standards. This introduces several improvements over standard Ethernet. Standard Ethernet communication is not time aware; it distributes the data over the entire bandwidth of the link with packets queued in order for transmission. TSN implements time awareness with scheduled traffic at configured offsets in cyclic intervals. That follows a schedule that is distributed by a network configuration controller.

Standard / IEEE Draft

Title

User’s Advantage

IEEE 802.1AS (evolving to P802.1ASrev) IEEE 802.1Qbv

Network Time Synchronization

All nodes share the same time

Scheduled Traffic Scheduled Ethernet frames never collide Filtering & Policing Removes babblers from the network (Security)

IEEE 802.1Qci

P802.1CB

Seamless Redundancy

Zero Loss switch-over

P802.1Qcc

Stream Reservation Path provisioning according to IEEE

IEEE 802.1Qbu and IEEE 802.3br

Frame Pre-emption

Maximum bandwidth without compromising real- time behavior

Figure 2. IEEE TSN Standards.

Further TSN features introduce Filtering and Policing for TSN streams, seamless redundancy and supports cyclic data transmission while also providing pre-emption for higher priority packets. TSN is defined by a set of IEEE 802.1 standards which specify the

implementation Figure 2). As of September 2017, four of these standards are adopted, while the remainder is still within the Task and Working Group stages. These standards are implemented over Ethernet (IEEE 802.3 Physical layer) and support star, chain,

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