A Distributed TSN Time Synchronization Algorithm with Increased Tolerance for Failure Scenarios

The integration of Industrial Internet of Things (IIoT) and Time-Sensitive Networking (TSN) enables efficient and reliable real-time communication and control. Currently, one of the current research hotspots in the field of TSN is the improvement of reliability in the use of IEEE 802.1AS(IEEE Standard for Local and metropolitan area networks - Timing and Synchronization for Time-Sensitive Applications). On one hand, IEEE 802.1AS does not provide specific steps for constructing redundant clock trees, and on the other hand, it cannot detect error time values caused by the failure propagation of devices on the clock tree. To address these issues, this paper proposes a Distributed time synchronization strategy based on IEEE 802.1AS(DAS). DAS utilizes a broadcast-based message exchange, and each endpoint device calculates its own synchronized time using fault-tolerant time synchronization methods. Furthermore, the time information is no longer embedded in data packets, avoiding the impact of erroneous time values on the time synchronization of other devices. Extensive simulations and on-board verifications are conducted on the DAS algorithm in this paper. The results show that the DAS algorithm can tolerate more failure scenarios while maintaining similar time synchronization accuracy compared to IEEE 802.1AS. Although the DAS algorithm consumes more bandwidth, this overhead is acceptable in small-scale networks. As far as we know, our work is the first in the industry to simultaneously achieve compatibility with existing 802.1AS and distributed TSN time synchronization, and to physically implement it in switch.