In Time-Triggered (TT) or time-sensitive networks, the transmission of a TT frame is required to be scheduled at a precise time instant for industrial distributed real-time control systems. Other (or {\em best-effort} (BE)) frames are forwarded in a BE manner. Under this scheduling strategy, the transmission of a TT frame must wait until its scheduled instant even if it could have been transmitted sooner. On the other hand, BE frames are transmitted whenever possible but may miss deadlines or may even be dropped due to congestion. As a result, TT transmission and BE delivery are incompatible with each other. To remedy this incompatibility, we propose a synergistic switch architecture (SWA) for TT transmission with BE delivery to dynamically improve the end-to-end (e2e) latency of TT frames by opportunistically exploiting BE delivery. Given a TT frame, the SWA generates and transmits a cloned copy with BE delivery. The first frame arriving at the receiver device is delivered with a configured jitter and the other copy ignored. So, the SWA achieves shorter latency and controllable jitter, the best of both worlds. We have implemented SWA using FPGAs in an industry-strength TT switches and used four test scenarios to demonstrate SWA's improvements of e2e latency and controllable jitter over the state-of-the-art TT transmission scheme.

翻译：在时间触发（TT）或时间敏感网络中，TT帧的传输需按照工业分布式实时控制系统要求的精确时间点进行调度。其他（即“尽力传送”BE）帧则以尽力服务方式转发。在该调度策略下，即使TT帧可以提前发送，也必须等待至其预定时刻才能传输。另一方面，BE帧虽可随时传送，但可能因拥塞而错过截止时间甚至被丢弃。由此导致TT传输与BE传送相互矛盾。为解决此矛盾，我们提出一种融合BE传送的协同交换架构（SWA），通过机会性地利用BE传送动态改善TT帧的端到端（e2e）时延。针对特定TT帧，SWA生成并发送一个采用BE传送的克隆副本。接收端设备交付先到达的帧（配置抖动容限），并丢弃另一副本。从而SWA实现了更短时延与可控抖动的双重优势。我们已在工业级TT交换机中基于FPGA实现SWA，并通过四个测试场景证明：相较于现有最先进TT传输方案，SWA能显著提升e2e时延性能并保持抖动可控。