Last edited one week ago

TSN overview

Applicable for STM32MP25x lines

1. Purpose

TSN stands for Time-Sensitive Networking, which is a set of standards developed by the IEEE (Institute of Electrical and Electronics Engineers) to provide deterministic and low-latency communication over Ethernet networks. TSN is designed to support real-time applications such as industrial automation, automotive, and audio/video streaming.

TSN achieves deterministic communication by providing time synchronization across all devices in the network, and by using traffic shaping and scheduling mechanisms to prioritize and allocate network resources for time-critical traffic. TSN also supports redundancy and fault tolerance mechanisms to ensure high availability and reliability.

Some of the key features of TSN include:

  • Time synchronization: TSN uses the Precision Time Protocol (PTP) to synchronize the clocks of all devices in the network with sub-microsecond accuracy.
    • IEEE 802.1AS-Rev
  • Traffic shaping and scheduling: TSN uses Quality of Service (QoS) mechanisms to prioritize and allocate network resources for time-critical traffic, and to prevent congestion and packet loss.
    • IEEE 802.1Qav
    • IEEE 802.1Qbv
  • Interoperability: TSN is designed to be compatible with existing Ethernet networks, and to support interoperability between different vendors and devices.

Overall, TSN provides a standardized and reliable solution for real-time communication over Ethernet networks, which can help to enable new applications and use cases in various industries.

The choice between 802.1Qav and 802.1Qbv depends on the specific requirements of the application. 802.1Qav is typically used in applications where bandwidth requirements are variable and unpredictable, while 802.1Qbv is typically used in applications where bandwidth requirements are fixed and predictable.

2. IEEE 802.1AS-Rev or gPTP synchronization

PTP is a protocol that enables the synchronization of clocks in a network. It uses a grandmaster architecture, where one device acts as the Grandmaster clock and the other devices act as ordinary clocks. The Grandmaster clock sends synchronization messages to the ordinary clocks, which adjust their clocks to match the Grandmaster clock.

Please see examples based on the following use cases:

3. IEEE 802.1Qav

IEEE 802.1Qav or CBS (Credit-Based Shaper) is a standard for time-sensitive networking (TSN) that provides a mechanism for the delivery of time-critical traffic over Ethernet networks. It defines a set of protocols and mechanisms that enable the transmission of audio and video streams with low latency and high reliability. The standard includes features such as time synchronization, traffic shaping, and stream reservation, which are essential for applications that require real-time communication, such as industrial automation, audio and video streaming, and automotive networking.

Please see examples based on the following use cases:

4. IEEE 802.1Qbv

IEEE 802.1Qbv is another standard for time-sensitive networking (TSN) that provides a mechanism for the delivery of time-critical traffic over Ethernet networks. It defines a time-aware shaper (TAS) that enables the transmission of time-sensitive traffic with deterministic latency and jitter. The TAS schedules traffic based on a time schedule, which is defined by the network administrator, and ensures that each traffic stream is transmitted within its allocated time slot. This standard is particularly useful for applications that require strict timing requirements, such as industrial automation, power grid control, and automotive networking.

Please see examples based on the following use cases:

5. References