| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a loop state detection device in a communication system of a frame relay system to surely detect a loop state when the completeness of a link is confirmed in a bidirectional PVC state confirmation procedure. SOLUTION: A state inquiry message transmission means 1a sets a 1st identification code at a prescribed position of the signal that transmits a state inquiry message and then transmits the state inquiry message. Receiving the message, a state answer message return means 2a produces a state answer message based on the state inquiry message, sets a 2nd identification code at a prescribed position of the signal and returns the state answer message to a 1st node 1. If a loop occurs on the circuit that is set between the 1st and 2nd nodes 1 and 2, a decision means 1b checks the codes set at each prescribed position when the state inquiry message is received and decides the occurrence of the loop when the 1st identification code is set at its prescribed position.</p> |
