Deterministic Ethernet refers to a networked communication technology that uses time scheduling to bring deterministic real-time communication to standard IEEE 802.3 Ethernet.
Deterministic Ethernet operates using a global sense of time and a schedule which is shared between network components.
By using Deterministic Ethernet, customers can converge real-time controls traffic with regular best-effort traffic on one Ethernet network. Time-scheduled traffic is partitioned from all other network traffic and is therefore immune from disturbance. This means that in a Deterministic Ethernet network, latency of critical scheduled communication is guaranteed. This is called Guarantee of Service.
Deterministic Ethernet is used in a wide range of applications where guaranteed latency is vital, either for reasons of operational efficiency or functional safety. These include autonomous driving, machine-to-machine communication and aerospace flight control.
Key Benefits
- Standards-based: Time-scheduled Ethernet standards such as IEEE 802.1Qbv TSN (pre-standard) and SAE AS6802 standards
- Partitioned: Virtual separation of traffic classes, enables convergence of other protocols on one physical network
- Compatible: Integrates installed industrial Ethernet protocols including Profinet and EtherNet/IP
- Scalable: Scales from small to very large systems without compromising safety, security or performance
- Secure: Existing security standards and management features implemented, partitioning prevents denial of service
The two key Ethernet technologies supported by TTTech are:
Fault-tolerant clock synchronization mechanism (SAE AS6802) is used to synchronize non-faulty networking components even in the present of faulty clocks. This provides Guarantee of Service for safety systems, even in the presence of faults (fail operationality).
Messages are forwarded in an extremely precise way, down to the individual packet. This enables a granular control over time-scheduled traffic.
Clock synchronization profile (802.1AS) based on 1588v2 is used to deliver global time.
Messages are forwarded as part of scheduled queues (802.1Qbv). This enables guaranteed latency in converged networks.
Background
Research at the Vienna University of Technology into time-scheduled distributed systems for the purpose of deterministic controls dates back to the early 1980s. Core elements of the architecture that came out of this research are clearly recognizable in Deterministic Ethernet such as Time-Sensitive Networking (TSN) and Time-Triggered Ethernet today. These elements include network-based clock synchronization, scheduling of critical resources and redundancy management as a platform service.
Deterministic Ethernet technologies share the core concepts of deterministic and reliable operation, but also the requirement to build upon standard components. From the original development of Time-Triggered Ethernet in 2006 for the NASA Orion spaceship (launched in 2014), time scheduling of Ethernet has been used in a range of aerospace, automotive and industrial applications. Since 2012, the IEEE Time-Sensitive Networking task group has been standardizing the core mechanisms of time scheduling in IEEE 802.1.
TTTech combines a deep knowledge of managing deterministic, high-availability networks with a long experience in delivering architectures and solutions for a wide spectrum of distributed applications.
