Blocking-Waived Estimation: Improving the Worst-Case End-To-End Delay Analysis in Switched Ethernet

As time-sensitive networks must guarantee the end-to-end delay requirement of data flows, the worst-case delay (WCD) analysis is mandatory. To date, several analytical approaches have been proposed for WCD analysis, mainly in two classes: network-calculus approaches (NC), and real-time scheduling-oriented approaches such as response-time analysis (RTA), and compositional performance analysis (CPA). In spite of advances in WCD analysis techniques, the computation of the exact worst-case delay faces combinatorial explosion issues, therefore several approaches have been developed to provide an upper bound with more or less pessimism. Nevertheless, reducing pessimism remains challenging, and each approach differs from others in specific scenarios. In this context, this paper provides a comprehensive comparative study that analyzes the results of WCD calculation approaches under the Non-preemptive Fixed Priority Scheduling Policy. To further reduce the pessimism, we propose a new algorithm BWE (Blocking-Waived Estimation) built for switched network architectures upon RTA, which further investigates the relationship between blocking time and transmission time of the flow of interest (e.g., virtual link in AFDX) in adjacent hops. As illustrated in an example network architecture, the result produced by BWE is generally less pessimistic (the WCD is reduced by at maximum 34.34%) compared to the state-of-the-art RTA/CPA calculation results.