Abstract: To overcome the drawback that switched Ethernet can not meet the real-time requirements in industrial communications, an improved message transmission model in which switch and the end-nodes controls the real-time traffic with Earliest Deadline First (EDF) scheduling was proposed. In addition, a distributed feasibility analysis method which is performed by the source and the destination nodes without the modification of the operational features of Ethernet switch was presented. Moreover, a more general condition for feasibility analysis for real-time periodic message over switched Ethernet was given and proved by using real-time theory.