How Time Sensitive Networking Can Create Low-latency Industrial Ethernet
Ethernet has improved significantly in various ways, including data speeds and latency, since its beginning in the early 1980s. However, the networking technology is still not deterministic by default and doesn’t support the latency levels required of today’s high-throughput industrial data communication right out of the box. Time-sensitive networking (TSN) is a set of IEEE 802 standards that are being developed to solve the latency issues of Ethernet by design.
Early Ethernet Improvements and Their Challenges
- Originally, Ethernet supported data rates of up to 10 Mb/s
- Wasn’t initially suited to real-time applications due to collisions at high utilization rates
- Switched networks solved Ethernet collision issues
- Quality of Service (QoS) improved processing with datagram prioritization
- Store and forward switches enhanced latency further, but not efficient enough when the network is over-utilized
Evolution of Ethernet Protocols
To improve Ethernet bandwidth reservation capabilities, automation engineers began developing numerous protocols that worked with special hardware. Examples include:
- Classic TCP/IP systems that utilized a field bus to control the bandwidth
- PROFINET IRT, which uses a time slicing technique to support bandwidth reservation
- EtherNet/IP, which uses QoS and is based on shared Ethernet cables
Introduction to Ethernet with TSN
TSN are protocols developed for Ethernet in line with IEEE 802.1 standards to address latency, determinism, and scalability issues.
Advantages of TSN
A time-sensitive network makes Ethernet more deterministic. The networking technology is expected to support a broad range of Ethernet applications in various industries, such as building automation and automotive. Its benefits include:
- Upward compatibility
- Multiple hard real-time uses
- Highly scalable (For example, TSN can quickly scale from 100 Mb/s to 5 Gb/s transmission rate and vice versa)
- TSN leverages unified layer 2 of the ISO/OSI Model and permits optimal utilization of Ethernet network topologies
- TSN solutions can be applied in a broad array of areas, including factory automation and energy distribution
- Installation and maintenance of TSN is much more streamlined compared with traditional Ethernet protocols
Transitioning to TSN
Logically, an immediate shift from existing industrial Ethernet protocols to TSN isn’t technically and economically feasible for most users. However, with special interfaces, a stepwise transition over 10 years or so is possible. For example, if you’re a PROFINET user, you may soon be able to access the protocol on TSN as layer 2. New TSN devices will make it possible for plants to safely migrate step by step, although users of Ethernet solutions like PROFINET RT won’t require any special hardware to make the switch.
As time-sensitive networking gradually catches on in the industrial data communications space, you’ll likely see more and more new installations set up based on the protocol from the ground up. In other scenarios, the technology is being incrementally incorporated in existing installations as part of a gradual Ethernet upgrade.
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