摘要 |
The present invention is intended to prevent from billing an unnecessary charge to an user by omitting AIS signals transmitted/received between a transmission side ATM unit and a receiving side ATM unit when a loss of service occurs in a communication network in which existing communication lines are connected by an ATM communication unit. In order to achieve the aforementioned goal, the transmission side ATM unit is adapted to monitor a signal received from a communication line on the transmission side and to stop the transmission of ATM cells to the receiving side ATM unit for a certain period of time when it detects an AIS signal indicating a loss of service on the transmission side and the receiving side ATM unit is adapted to monitor a state for receiving the ATM cells transmitted from the transmission side ATM unit and when it recognizes that the receiving of the ATM cells is stopped for a certain period of time, to generate an AIS signal indicating the loss of service on the transmission side and to send it on the communication line on the receiving side.
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