Abstract: A Local Area Network (LAN) is disclosed in which each node includes means for receiving clock signal information from an external network, which may by way of example be another LAN or a wide area network (WAN), and for generating therefrom clock signals for each node of the local network to accommodate synchronous information exchanges with the external network. Any one of the nodes of the local LAN network may act as a Control Node, and any one of the remaining nodes upon instruction from the Control Node may act as a primary Transmission Node for generating clock signals based upon the external network clock signals for all of the nodes of the local LAN network.

Abstract: A method for performing a duplicated address test used for a network including a first ring transmission line, a second ring transmission line having a signal transmission direction opposite to that of the first ring transmission line, and a plurality of stations connected to at least one of these ring transmission lines. Each of these stations has a flag DAC representing whether or not the duplicated address test is performed, and some of the plural stations constitute a plurality of control nodes having a configuration function of the network. The flag DAC of each of the stations is reset at a time instant when a power source of this station is turned on, and also when any of the control nodes receives the sent out configuration control frame. Each of the stations having the reset flags DAC sents out the duplicated address test frame to either the first or second transmission line to which the station is connected when a token frame to control a transmission right is captured.