| 摘要 |
PROBLEM TO BE SOLVED: To maintain the line quality by providing a means detecting a flow of cells flowing in or flowing out to each device being a component of an ATM network system to each device. SOLUTION: When a state of line quality is detected, a CPU control means revises a VPI latch start/stop bit in a periodic monitor cell into '0' to stop the operation of a VPI latch section 101 and to stop count of a VPI CTR section 102. Then a CPU IF section 103 is used to retrieve a count of the VPI CTR section 102. Total number of VPI cells inserted from a data input side and the value retrieved by the VPI CTR section 102 are compared, and when the retrieved value is smaller, it is discriminated that loss of cell is produced between packages, and when the retrieved value is larger conversely, it is discriminated that mis-delivery of cells is produced between packages so as to attain the line quality monitor of the system including the detection of cell flow, loss and mis-delivery.
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