关键词: 网络演算, 交换式以太网, 时延上界

Abstract: The focus that switched Ethernet is applied in the networked control system is ability of real-time.For this，a new analytic tool：network calculus is used to determinately analyze the special performances of the real-time data via a switched Ethernet.With scheduling algorithms FIFO（First Input First Output），the communication model is set up and network elements’ arrive curves and service curves are derived for a switched industrial Ethernet model with two levels’ tree topology.Then，analytic expressions of the worst case end-to-end delay，buffer size and output burstiness are presented，the maximum network delays of real-time data are calculated based on derived results.

Key words: network calculus, switched Ethernet, worst case delay bound