主从交换式以太网中跨多Switch传输消息实时调度研究

Research on real-time messages transmission scheduling over master-slave-based multi-switch Ethernet

针对FTT-SE协议在单Master多交换机的网络扩展结构中存在的消息跨多Switch传输调度问题,给出了消息在每个基本调度周期内到达各交换机输出端口时间的计算方法,提出了单EC内的消息可调度性判定算法,并对算法的可行性进行了证明。在此基础上,设计了基于EDF的消息实时调度算法和准入控制算法。通过确定消息在每个基本调度周期内到达各交换机输出端口时间,所提出的调度算法能针对COTS交换机输出端口的FCFS消息传输机制,实现对单EC内消息传输的精确控制和调度。相对已有的调度算法,仿真实验表明,所提出的算法能更有效地利用网络带宽,提高了主从交换式以太网通信的实时性。

To schedule the messages transmission over master-slave-based multi-switch Ethernet and meet the real-time requirements, we propose a method for calculating the arrival time of the messages scheduled in each elementary cycle to the switch output. In addition, we also present a novel feasibility analysis algorithm called ECSchedTest f for periodic real-time messages scheduled in one elementary cycle, and prove its correctness. Moreover, an EDF-based real-time scheduling algorithm and an admission control algorithm for periodic messages are presented to take full advantage of multiple transmission paths of the switched network. In every elementary cycle, by calculating the time of each message＇s arrival to the output ports of the switches that it traverses, and considering the FCFS message scheduling policy used in the switch, the scheduler with ECSchedTest can handle the message transmission precisely and efficiently. Simulation results show the advantages of the proposed real-time scheduling algorithm in terms of the network bandwidth utilization, thus enhancing real-time communication over a masterslave-based multi-switch Ethernet.