Abstract: In an input cell policing method in a network of an asynchronous transfer mode, according to information contained in a header field of each input cell, a group to which the cell belongs is identified. For each group, there are set a plurality of time frames having a predetermined length and mutually different phases to count the number of input cells in each time frame period. For each time frame, the count value of input cells is compared with a predetermined threshold value. An input cell for which the count value exceeds the threshold value in either one of the time frames is assumed to be an excess cell. The excess cell is discarded or a violation mark is added thereto.

Abstract: A UPC circuit fault diagnosis system for diagnosing a failure in a UPC circuit controls cell traffic volume on the basis of prescribed information about cell traffic. Failure diagnosis of a UPC circuit is provided by a usage parameter determination of at least one kind of cell, using more than one system and comparing determination results. The diagnosis system has an operating UPC circuit for controlling a total of m kinds of cells, and a standby UPC circuit for controlling a total of n kinds of cells. The system also has a total of q bridge memories for keeping a chronological record of the prescribed information of arriving cells. A fault diagnosis of the bridge memories is provided by comparing the contents of the bridge memories, using more than one system.

Abstract: A monitor system for a multiplex equipment, comprising a multiplexing unit for multiplexing low speed group input signals of plural channels into a high speed group output signal and a demultiplexing unit for demultiplexing a high speed group input signal into low speed group output signals of plural channels, wherein the high speed group output signal and the low speed group input signals on one hand and the high speed group input signal and the low speed group output signals on the other hand are monitored through comparison on the basis of the low speed group signal. When discrepancy is detected in the comparison between the high speed group output signal and the low speed group input signal in a certain channel of the low speed group signal in the course of monitoring the multiplex unit, the comparison between the high speed input signal and the low speed output signal is performed in a different channel of the low speed group signal for monitoring the demultiplex unit.