| 摘要 |
A looping detection apparatus used in a frame-relay communications system and capable of detecting looping without fail through confirmation of link completeness according to a two-way PVC status confirmation procedure. A status enquiry message transmitting unit transmits a status enquiry message with a first identification code carried at a predetermined position of a signal by means of which the status enquiry message is transmitted. On receiving the status enquiry message, a status response message returning unit creates a status response message based on the status enquiry message and sends the status response message back to a first node with a second identification code carried at the predetermined position. When a status enquiry message is received, a judging unit checks the code carried at the predetermined position to determine whether or not a loop has occurred in the channel between the first and second nodes, and judges that a loop has occurred in the channel if the received message carries the first identification code.
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