AFDX网络传输性能分析

AFDX Network Transmission Performance Anal Ysis

摘要:

AFDX(avionics full duplex switched ethernet) 作为一种基于Ethernet技术的全双工数据交换航空电子数据总线,它不仅避免了Ethernet数据传输冲突和碰撞的问题,而且在减轻重量的基础上提高了数据传输率；在设计的过程中,为了保证数据传输的实时性和可靠性,确保数据传输的确定性和无丢失服务,网络传输性能测试分析是设计人员必须考虑的问题；由此一种简单快捷的基于网络演算 NC(network calculus)理论进行总线性能传输和测试的方法被推导出来,目的是通过数学评估和仿真的手段分析不同航空电子AFDX数据总线和网络拓扑结构的传输性能,分析的主要目的针对3个重要的网络延迟参数指标(延迟、预留缓冲区和输出数据流)；开展这方面的研究有利于在航电总线设计初期帮助设计人员发现问题,尤其是应用于保证航电数据总线无丢失确定性服务方面；除此之外,还比较了目前存在的延迟计算的几种常用方法,并通过仿真举例说明了这种方法的应用。

Abstract:

AFDX(Avionics Full Duplex Switched Ethernet) is the high-speed full duplex switched avionic databus, on the basis of the Ethernet technology. AFDX can not only avoid Ethernet conflicts and collisions,but also increase transmission rate with a lower weigh of the databus. The avionics data must be delivered punctualy and reliablely, so it is very essential to validate the real-time performance of AFDX during the design process. Aims to guarantee the lossless service in avionics databus, based on NC(Network Calculus),a smart method has been deduced to assess the transmission performance of different network topologies in different avionics architectures through the simulatin and the mathematical assessment,mainly considering three important parameters(delay,backlog and output flow). The technologies used in this thesis benefit to find problems and faults in the beginning stage of the avionics architecture design in the industrial project, especially, in terms of guarantee the lossless service in avionics databus.Several current methods for calculating delay have been listed here, and using some simulation exemples illustrates the way to apply it in conceret scenario.