METHOD FOR ASSIGNING IDLE CELL WITH PRIORITY IN ATM-M BUS SYSTEM AND BRANCHING DEVICE USED FOR THIS METHOD

摘要

PROBLEM TO BE SOLVED: To ensure communication quality by eliminating a delay of data and its fluctuation where real time performance is a requirement for a voice communication or the like on a congested ATM-M bus. SOLUTION: The method is an assignment control method of idle cells with priority in an ATM-M bus system where a plurality of branching devices 30 are connected in cascade to an M bus 20 in which an outgoing bus 21 connected to an ATM master unit is looped back at a loopback section 32 of a downstream of a branching device 30-2 at the remotest end and becomes an incoming bus 22. Information denoting whether a terminal requires assignment of an idle cell with priority or a terminal which does not require the priority assignment of the idle cell is set to contents of an 'AAL parameter' information element in a 'setup message' that is sent from a terminal 50 contained in a branching device 30 to the ATM master unit (MBU 12) in the case of call transmission, and the MBU 12 assigns a cell 42 specifying a destination of use to a branching device 30-1 holding a terminal 50-1 requiring assignment with priority and transmits it to the branching device 30-1.