Performance Comparison of IEEE 802.1 TSN Time Aware Shaper (TAS) and Asynchronous Traffic Shaper (ATS)

The IEEE 802.1 time sensitive networking working group has recently standardized the time aware shaper (TAS). The TAS provides deterministic latency guarantees but requires tight time synchronization in all network switches. This paper thoroughly evaluates the mean and maximum packet delays and packet losses of the TAS for a typical industrial control ring network for random (sporadic) and for periodic traffic. We propose and evaluate adaptive bandwidth sharing and adaptive slotted window mechanisms to make TAS adaptive to traffic fluctuations. This paper further evaluates the asynchronous traffic shaper (ATS), which has been proposed to provide low latency network service without the need for time synchronization in network nodes. Our evaluations indicate that TAS with proper configurations, e.g., accurate and precise gating schedules, generally achieves the specified latency bounds for both sporadic and periodic traffic. In contrast, ATS performs relatively well for sporadic traffic; but struggles for moderate to high loads of periodic traffic.