The research of scheduling algorithm for time-triggered ethernet based on path-hop

The time-triggered principle establishes and maintains a system-wide synchronized time-base by the local clocks of the device. The proposed concept of Time-Triggered Ethernet (TTE) guarantees the determinacy of time-critical message for avionics and safety-critical systems. This paper presents an algorithm based on path-hop of tasks to generate a rational scheduling timetable to ensure is free of conflicts on the physical link. The scheduling timetable is periodic cycle by the Cluster Cycle as a unit. Cluster Cycle consists of several Integration Cycles (Min-cycle) with same time span. Time-Triggered (TT) flows are divided into several types by their path-hop parameter which can be obtained from path property. Different types of TT flows can be arranged into Cluster Cycle without conflict to achieve temporal determinacy. Meanwhile, the scheduling timetable unifies TT traffic and RC (Rate-Constrained) traffic defined in Avionics Full Duplex Switched Ethernet (AFDX) as well as BE (Best-Effort) traffic defined in ordinary Ethernet to improve bandwidth utilization. When all TT flows have been arranged into the scheduling timetable, the residual time resource can be used to transmit RC frames. Each vertex in the TTE network has its own scheduling timetable with different contents. Due to the clearly divided of timetable, it can support on-line modification for dynamical task insertion and withdrawal without congestion.