Patent ID: 6259696
Filing Date: 2001-07-10
Classification: H04L,H04Q

Abstract:
An asynchronous transmission mode switch comprising:a plurality of input line interface units provided at every plurality of input lines;a plurality of output line interface units provided at every plurality of output lines; anda switch core unit connected to said plurality of input line interface units and said plurality of output line interface units for switching cells inputted from said input line interface units to any one of said output line interface units or packet-level-discarding said cells, wherein said switch core unit includes a packet level discard control table for holding at every connection a packet level discard priority indicating whether or not other ATM switches not having a packet level discard function exist in the upstream of connections, and discards cells from ATM switches not having the packet level discard function prior to other cells, and wherein said switch core unit further includes a first congestion detection circuit for detecting a congestion state within said switch core unit and only when the detected result of said first congestion detection circuit indicates a predetermined congestion state, cells from other ATM switches having said packet level discard function not implemented are discarded with a priority to other cells, and wherein said switch core unit further includes a second congestion detection circuit for detecting a congestion state of other ATM switch through which said cell is transmitted based on a congestion indication bit within said cell and only when a detected result of said first congestion detection circuit indicates said predetermined congestion state, of the cells which are judged to be transmitted via other congested ATM switch by the second congestion detection circuit, cells transmitted via other ATM switch not having the packet level discard function are packet-level-discarded with said priority to other cells.