Patent ID: 7549088

Claim:
A method of determining a failure in an information system, the system including a transmission apparatus to transmit control information and a reception apparatus connected to the transmission apparatus in such a manner as to enable information to be transmitted and received, the reception apparatus to receive the control information and to transmit response information to the received control information, comprising: obtaining, as a first clock time, a clock time of the most recently transmitted control information if the response information to the control information cannot be obtained within a predetermined time period; obtaining, as a second clock time, a later one of a clock time of the response information most recently transmitted by the reception apparatus and a clock time of the control information most recently received by the reception apparatus; and determining a failure location based on A) a type of control information indicating whether control information is transmitted control information or received control information and B) a before/after relationship of the first clock time and the second clock time.