We are delighted to announce that RTaW-Pegase now fully supports Time-Sensitive Networking (TSN) timing QoS mechanisms in both worst-case traversal time analysis and timing-accurate simulation. This includes support for priorities, preemption, AVB/CBS, TAS, and ATS shapers.

TSN: The Next Generation of Real-Time Ethernet

Established in 2012, the IEEE 802.1 TSN Task Group has been developing and standardizing technologies to meet quality of service (QoS) requirements related to timing and reliability over Ethernet. Key mechanisms providing predictable and deterministic timing behaviors have been introduced in amendments like IEEE 802.1Qbv (Time-Aware Shaper—TAS), IEEE 802.1Qbu (Frame Preemption), and IEEE 802.1Qcr (Asynchronous Traffic Shaper—ATS). These enhancements add to the well-known Credit-Based Shaper (CBS) standardized in IEEE 802.1Qav, which predates TSN.

Combining Multiple QoS Mechanisms at a Single Output Port

TSN enables the use of multiple QoS protocols simultaneously at a single egress port, going beyond simple priority usage. This flexibility opens up a vast array of design possibilities. However, ensuring timing predictability remains crucial for mission-critical networks. RTaW-Pegase supports various combinations of QoS mechanisms suitable for a wide range of practical use cases and provides network-calculus-based worst-case analysis for each configuration.

For example, at each egress port, you can combine ATS with CBS or TAS with CBS. The QoS mechanism for each queue can be selected independently, and importantly, CBS and ATS can be applied at any priority level and across multiple queues. The QoS mechanism for each queue can be selected independently, and importantly, CBS and ATS can be applied at any priority level and across multiple queues.

Time-Triggered Traffic and Exclusive Gating

RTaW-Pegase also supports “time-triggered traffic” (also known as “scheduled traffic,” as defined in IEEE 802.1Qbv) with reserved transmission windows for one of the eight queues. TSN uses a gate control system based on a schedule—the Time-Aware Shaper—to allow or prevent certain queues from transmitting packets during predefined time intervals. The most common configuration strategy is “exclusive gating,” where the highest-criticality traffic has exclusive access to the link during specific intervals, while other traffic classes access the link outside these times.

With RTaW-Pegase, you can also model frame preemption for each queue, offering for certain use-cases an alternative to TAS for reducing interference from low-priority packets (interested in the different types of interferences on a TSN network? Consult this post).

Exclusive Features of RTaW-Pegase

  • Unified Environment: RTaW-Pegase is the only tool that offers both simulation and worst-case analysis within a single environment.
  • Comprehensive QoS Combinations: It uniquely allows the combination of CBS, TAS, priorities, and ATS at a single output port, accounting for the timing interactions between schedulers.

Interested in network calculus research? Check out this page.