Time-Triggered Switch-Memory-Switch Architecture for Time-Sensitive Networking Switches

Abstract

Time-sensitive networking (TSN) is a set of extended standards for the IEEE 802.3 Ethernet under development by the IEEE 802.1 TSN task group. TSN depends on two key components, scheduling and fault tolerance, to provide real-time and reliable transmission. There is a strong motivation to replace the widely used field-buses with TSNs in industrial networking applications. However, industrial network devices are typical application-specific embedded systems with limited memory resources. Time-sensitive (TS) transmission certainly prefers on-chip memory, which is even more scarce for embedded systems. As a result, it is critical for TSNs to develop memory-efficient switching techniques with scalable schedulability and elegant fault-tolerance support. This paper proposes a time-triggered switch-memory-switch (SMS) architecture for memory-efficient TSN switches. First, based on the SMS shared memory, our architecture makes it possible to statically schedule memory allocation with full utilization for TS traffic and the remaining memory for other traffic. Compared with per-port memory, the shared memory achieves a ratio of ( ${n^{n}}/{n!}$ ) ( ${\approx }({e^{n}}/{\sqrt {2 \pi n}}), {n\rightarrow \infty }$ ), where ${n}$ is the port number, in the feasible solution space under memory constraints and thus significantly improves scheduling memory ability and flexibility. Moreover, we develop a fault-tolerance scheme for reliable transmission. It facilitates a memory-efficient implementation of the popular multiline redundancy in industrial networks. The scheme is validated by five classes of memory conflicts and a case study on two-line redundancy.