The conclusion that the optical fiber ring shaped local area network in the optimal integrated service network in the future has been put forward according to the discussion of the present situation and the tendency of LAN development，the frame structure fit for integrated service switch in LAN has been put forword，a layered description of the communication protocol has been given，the method realizing boundary movement has been put forword，and the software based on the form of messages and tactics of boundary movement has been realized.