DATA COMMUNICATION SYSTEM

PURPOSE:To attain the mutual data transmission/reception independently of the configuration of a physical network by installing a protocol converter to a connecting point between a local area network (LAN) and other communication medium and applying virtual processing to the communication medium other than the LAN into an LAN ring. CONSTITUTION:An equipment 3 applying protocol conversion is provided to a connecting point with a broad band network 6 and a connecting point with a host computer 4 while taking an address system of a data link layer of a local area network and a protocol are taken as a basis of all network in common. The data link layer of the local area network is used as a common layer of a network architecture, then each constituting equipment of the network has only to support one kind of communication protocol defined as a homogeneous network independently of the type of the network configuration even with optional combination of the equipments, the mobility of each constituting equipment, the single model and the flexibility against the revision in the network constitution are improved.