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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.
Figure 1
. Automation Pyramid with typical assignment of networks to hierarchies.
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,
Standard / IEEE
Draft
Title
User’s Advantage
IEEE 802.1AS
(evolving to
P802.1ASrev)
Network Time
Synchronization
All nodes share the same
time
IEEE 802.1Qbv
Scheduled Traffic Scheduled Ethernet frames
never collide
IEEE 802.1Qci
Filtering & Policing Removes babblers from the
network (Security)
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
26 l New-Tech Magazine Europe