DEVICE FOR MONITORING QUEUE STATE IN ASYNCHRONOUS TRANSFER MODE SWITCH AND METHOD THEREOF

摘要

PURPOSE: A device for monitoring a queue state in an asynchronous transfer mode(ATM) switch is provided to perceive the queue state of the ATM switch in a subscriber board of an ATM exchange system, so as to control an available bit rate(ABR) traffic. CONSTITUTION: A memory stores an inputting time of a resource management(RM) cell and an outputting time of the transmitted RM cell. A forward resource management(FRM) processor detects an inputting time of a former RM cell stored in a memory when the RM cell is inputted from a source, and calculates a time difference between the inputting time of the RM cell and the inputting time of the former RM cell to insert the time difference into a FRM cell transmitted to a switch. A backward resource management(BRM) processor detects an outputting time of the former RM cell stored in the memory when the FRM cell is outputted from the switch, and calculates a time difference between the outputting time of the FRM cell and the outputting time of the former RM cell, then calculates the difference between an inputting time difference and an outputting time difference to insert the difference into a BRM cell transmitted to the switch. A speed calculator confirms a difference value between the inputting time difference and the outputting time difference of the BRM cell transmitted from the switch, and calculates an explicit cell rate(ER) value and a scheduler rate(SR) value. A speed controller decides a switch queue state by the difference value, and controls a cell transmitting speed according to the ER value and the SR value.