RELIABLE FIBEROPTIC NETWORK: THE AUTONOMOUS DECENTRALIZED LOOP NETWORK.

Recently, distributed processing systems have been increasingly developed, thanks to advancements in LSI technology and optical transmission technology. In large-scale real time systems such as train traffic control, factory automation and process control systems, the requirements of fault tolerance, on-line expandability and on-line maintainability are intrinsic. For the purpose of meeting the above system requirements, we have proposed a new system concept, an autonomous decentralized system concept based on a biological analogy. In distributed systems, local area networks are indispensable for communication among subsystems. They also have to meet the above system requirements. Thus, we have developed a double loop network system based on an autonomous decentralized system concept. In this network, each NCP (network control processor) of each node has autonomy in fault detection, fault recovery, transmission and maintenance. The optical fiber cables enable the NCPs to electrically insulate themselves, and prevent the physical faults of each NCP from influencing the other NCPs.