交换式以太网的实时性能分析是工业以太网研究领域的一个热点课题，目前还没有一个有效的数学模型来对其进行描述。通过对典型交换机结构的分析，应用网络微积分理论建立了交换机的服务曲线模型，该模型将交换机中的数据流分为实时数据和非实时数据，并得到了最大延迟值和最大缓存需求值等，最大延迟为交换机的实时应用提供了理论边界值，最大缓存需求值为在实时工业环境中的交换机构建提供了理论参考。

The real-time performance of switched Ethernet is a hot research field. However, there isn't an effective modeling to describe it until now. Through analyzing the structure of classical switch, a switch model by network calculus is proposed, in which the data flow is divided into real-time flow and non-real-time flow and the arrival curve, service curve, the max delay and max storage needed are got. The max delay provides theory direction for transmitting real-time data in switched Ethernet and the max storage provides the theory reference for constructing switch in real-time industrial Ethernet.