TTE网络流量转换策略及其延时性能保障调度算法研究

时间触发以太网（TTE）通过精确的全局时钟同步，使时间触发（TT）消息具有了严格的时间确定性。当系统同步精度降低时，TT消息的实时性也将严重受到影响。利用TTE交换机的流量类型转换功能，提出了一种基于消息时间窗检测的转换策略（TT-TWD）。该策略应用于TT流量向速率限制（RC）流量的转换过程，能够避免在系统同步精度降低时，TT消息出现丢包或不可接受延迟的情况。为保障该策略下网络流量的实时性，设计了一种基于流量转换策略的优先级调度算法（PTCTS）。运用网络演算理论对PTCTS算法的实时性进行了分析，并与先入先出（FIFO）算法结果对比，证明了PTCTS算法有效地减小了由TT流量转换而来的RC流量的延迟上界，同时保证了原始RC流量端到端延迟的确定性。

Research on Traffic Classes Transformation Strategy and Real-time Guarantee Scheduling Algorithm in TTEthernet

A strict time determinism of time-triggered (TT) messages in time-triggered ethernet (TTE) is established on the basis of precise system clock synchronization. When the system synchronization status deteriorates, the TT messages' time determinism will be greatly affected. For TTEthernet switch traffic classes transformation capability, a TT transformation strategy based on the time windows detection (TT-TWD) is proposed in this paper. The transformation strategy allows the TT data to avoid losing or having an unacceptable delay when the system synchronization accuracy is reduced. In order to guarantee the strategy performance, a scheduling algorithm (Priority scheduling algorithm based on Traffic Classed Transformation Strategy, PTCTS) is designed. Real-time performance of PTCTS algorithm is analyzed using network calculus theory. The performance of PTCTS algorithm and first-in-first-out (FIFO) scheduling algorithm is compared. The results confirm that PTCTS algorithm can effectively lower the upper delay bounds of the rate-constrained (RC) traffic which is transformed from TT without losing the determinism of the original RC data.