航空电子全双工交换式以太网(AFDX)是针对航空电子应用从工业交换式以太网升级而来的。其中,引入的虚拟链路(VL)和流量管制机制为网络通信任务提供了确定性的保障。网络演算是AFDX中常用的VL延时上界计算工具,为AFDX网络的实时性研究提供了理论依据。但是网络演算采用了VL简单流模型,计算得到的延时上界比较悲观。将VL精确流模型应用在网络演算工具中,并展示了基于精确流模型的网络演算能够得到更紧的延时上界计算结果。 Avionics Full Duplex Switched Ethernet (AFDX) is an upgrade from industrial switched Ethernet for avionics applications. Among them, the introduction of the virtual link (VL) and traffic control mechanisms for network communications tasks provide a deterministic guarantee. Network calculus is commonly used in AFDX VL delay upper bound calculation tool, which provides a theoretical basis for the real-time study of AFDX network. However, the VL simple flow model is adopted in the network calculus, and the calculated upper bound of the delay is rather pessimistic. The VL precise flow model is applied to the network calculus tools and shows that the network calculus based on the accurate flow model can obtain tighter time delay upper bound calculation results.