NETWORK SYSTEM, TERMINAL DEVICE, MANAGEMENT DEVICE, AND NETWORK MONITORING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a network system capable of mitigating a processing load of a communication device and performing failure detection, without implementing a specific protocol.SOLUTION: A network system comprises: a management server; a plurality of communication devices whose communication path is set by the management server; and a user terminal connected to the communication device. A user terminal 1-1 connected to one communication device of the communication devices comprises: a communication interface unit 11 for performing communication with an opposing user terminal connected to another communication device; a failure detection unit 121 for detecting a failure in a communication path with the opposing user terminal on the basis of the presence/absence of an answer from the opposite user terminal; and a failure occurrence notification unit 122 for transmitting failure occurrence notification including failure information for identifying a communication path in which a failure is detected in the case where the failure is detected, to the management server.