A LAN connecting device connectable to a LAN and connected to its opposite party device through lines 202 and 203 each using an optical fiber as a physical medium is provided with a communication data control portion 208 for performing an ordinary LAN communication between terminals of a physical communication or between terminals of a logical communication, a maintenance data control portion 218 for performing a test of communication, and an optical multiplexer 211 and an optical demultiplexer 213 for multiplexing and demultiplexing the input/output wavelengths of the communication data control portion 208 and the maintenance data control portion 218, and optionally performs a test of communication by means of the maintenance data control portion 218, and therefore, even such a LAN connecting device as a bridge, switch, repeater or the like not having a protocol up to the OSI layer 3 makes it possible to perform a test of a path between communication terminals, between repeating devices or between a communication terminal and a repeating device, and perform an operation test on these communication terminals and repeating devices

Maintenance test system between lan connection devices and lan connection device

This paper describes an optical fiber Ethernet repeater system to transmit two-way Ethernet data for controlling machines Ethernet data used for controlling machines is transferred between a pair of computers connected through a GI multimode optical fiber and a pair of optical fiber repeaters which are compatible with Ethernet systems A new type of optical repeater is fabricated using the optical transmitter/receiver and Ethernet repeater circuit This new type of optical-repeater is simpler than the conventional fiber optic inter-repeater links in construction, and this type of local area network can be constructed at low cost for controlling machines from a remote point if this new type of optical repeater is used

S. Isogai

Papers

Optical fiber Ethernet data transmission