Effective Routing and Scheduling Strategies for Fault-Tolerant Time-Sensitive Networking

Time-sensitive networking (TSN) Task Group of the IEEE proposed the frame replication and elimination for reliability (FRER) technique to guarantee reliable transmissions in TSN for the emerging Industrial Internet of Things (IIoT). FRER is a technique that manages the replication and elimination of frames of a stream sent through multiple paths as member streams. However, the standard does not specify how to find and select the multiple paths to send the replicated member streams on, nor how the time-aware shaper (TAS) should be scheduled considering frame elimination. Most prior work on routing or TAS scheduling in TSN do not consider FRER. Conversely, studies on FRER do not address the routing and scheduling issues effectively. In this article, we propose multipath routing and TAS scheduling strategies to support FRER in TSN with reduced complexity. We also identify a scheduling deadlock problem due to the unique characteristics of FRER, and propose a solution using topological sorting. Then, we propose two metaheuristic optimizers to increase the TAS scheduling success rate. Through extensive evaluation against state-of-the-art prior work, we show that our strategies can support more flows with reduced utilization and enhanced schedulability while effectively handling the complexity of routing and scheduling problems for FRER.