Access mechanism for period flows of non-deterministic end systems for time-sensitive networks

Abstract

The IEEE 802.1Qbv standard schedules time-triggered (TT) flows (i.e., period flows) in a fixed TT Window each period. However,period flows generated by non-deterministic end systems exhibit significant jitter, whichleads to a mismatch between the generation times and the scheduled TT Windows. In the worst case scenario, this mismatch can cause an additional send delay of approximately one period in the flow. In this study,we model the send delay issue due to the maximum send delay requirement for all frames in a period flow not being satisfied simultaneously, and measure the jitter of period flows in a typical non-deterministic end system. Moreover, we propose an access mechanism for jittered period flows to schedule multiple conflict-free TT Windows in each period of flows at the source end system and control the send delay within the required delay tolerance. This mechanism enables deterministic access to jittered period flows, providing a prerequisite for reliable end-to-end transmission in the network. Moreover, this mechanism adopts a multi-objective integer linear programming (MILP) solver to optimize the TT Windows schedule. Furthermore, we establish the constraints and objective functions for the MILP solver and evaluate the mechanism with actual sampled frames in a real non-deterministic end system. Compared with the conventional fixed single TT Window and worst-case delay analysis mechanisms, the proposed mechanism satisfies the send delay requirements and considerably reduces the buffer usage at the source end system.