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US 6,122,251 AGranted
Switch control circuit and control method of ATM switchboard
AssigneeNEC Corporation
InventorMasayuki Shinohara
Life of this patent
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AssigneeNEC Corporation
InventorMasayuki Shinohara
Estimating the term…
To realize the traffic control for controlling congestion in an ATM switchboard and assuring the throughput of VCs using the same output port. A buffer occupancy value measuring section measures the queue length of each of the output port buffers and stores the data in a buffer occupancy value table. A back-pressure outputting section outputs a transmission restart signal when a queue length in the buffer occupancy table is equal to or less than a fist threshold, a transmission control signal when the queue length is between the first threshold and a second threshold, and a transmission stop signal when the queue length is equal to or more than the second threshold as back pressure signal respectively. A cell transmission control section transmits an ATM cell without comparing a transmission time with the present time when the instruction of a back pressure signal corresponding to a destination port indicates "restart" and transmits an ATM cell only when the transmission time is earlier than the present time if the instruction indicates "control".
A switch control circuit of an ATM switchboard for switching ATM cells transferred in an asynchronous mode between an input port and an output port, said circuit comprising,
A switch control method of an ATM switchboard for switching an ATM cell transferred in an asynchronous mode between an input port and an output port, the method comprising the first step of outputting any one of a transmission restart signal, transmission stop signal, or transmission control signal in accordance with an occupancy value of said output port buffer in order to prevent cells in said output port buffer corresponding to said output port from being inefficiently used and the second step of performing control so as to transmit said ATM cell at a preset first rate to an output port for transmitting said ATM cell when said transmission restart signal is input in said first step corresponding to said output port and transmitting said ATM cell to an output port for transmitting said ATM cell at a preset second rate when said transmission control signal is input in said first step corresponding to said output port.
Dependencies are inferred from the claim text.