A Time-Aware Shaper-Based Method for Addressing Traffic Bursts and Out-of-Order Induced by IEEE 802.1CB in In-Vehicle Networks

The trends of intelligence and connectivity are continuously driving innovation in automotive technology. With the deployment of more safety-critical applications, the demand for communication reliability in in-vehicle networks (IVNs) has increased significantly. As a result, Time-Sensitive Networking (TSN) standards have been adopted in the automotive domain to ensure highly reliable and real-time data transmission. IEEE 802.1CB is one of the TSN standards that proposes a Frame Replication and Elimination for Reliability (FRER) mechanism. With FRER, streams requiring reliable transmission are duplicated and sent over disjoint paths in the network. FRER enhances reliability without sacrificing real-time data transmission through redundancy in both temporal and spatial dimensions, in contrast to the acknowledgment and retransmission mechanisms used in traditional Ethernet. However, previous studies have demonstrated that, under specific conditions, FRER can lead to traffic bursts and out-of-order, which are intolerable for safety-critical applications. Current research has analyzed the causes of traffic bursts and out-of-order delivery, but effective preventive solutions have yet to be proposed. To address these issues, this paper first employs a formal method to demonstrate that intermittent streams cannot satisfy the conditions for generating traffic bursts and out-of-order. Subsequently, a novel intermittent stream constraint is proposed, and basic constraints for time-aware shaper (TAS) are extended to support redundant communication. Finally, a TAS-based method is implemented, which ensures that traffic is shaped into intermittent streams when FRER is used. Simulation results in OMNET++ indicate that the TAS-based method proposed effectively avoids traffic bursts and out-of-order issues after recovery from link failures in IVNs.