REDUNDANCY SYSTEM OF COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To construct a system that is inexpensive and redundant by controlling the switching of two adjoining node devices that bidirectionally connect plural node devices in a loop shape, based on a result of mutually supervision of an operation state and functioning it as the current system or a spare system to one communication terminal. SOLUTION: Two ATM exchange devices 0 if a node B can notify a mutual state via an Ethernet (R) interface 9 and are connected to a common terminal device 11 via a switching device 10. The device 11 is capable of communicating with both of two current and spare system ATM exchange device 0 by switching the device 10. The current and spare system ATM exchange devices 0 are communicable and incommunicable with the device 11, because an ATM switch 12 is connected to or disconnected from a terminal interface 7. Thus, it is possible to obtain a system that is inexpensive and redundant without the use of an additional device, such as opticals coupler and light switches.