ATM cell assembling/disassembling apparatus
AssigneeNEC Electronics Corporation
InventorSatoshi Katayanagi
Life of this patent
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Abstract
The present invention provides an ATM cell assembling/disassembling apparatus capable of reducing power consumption. A reception VC detector 16 decides whether a reception cell is valid. A reception controller 17 performs disassembling and error check of a cell which has been decided to be valid by the reception VC detector 16 before issuing a DMA transfer request. A DMA output block 12 reads out a reception payload data from a reception data buffer 18 and DMA-transfers the data to a host memory 3. A reception clock controller 20 starts clock supply to the reception controller 17 when the reception VC detector 16 has decided that the reception cell is valid, and terminates the clock supply to the reception controller 17 upon completion of processing for one cell in the reception controller 17.
Claims6
An ATM cell assembling/disassembling apparatus arranged on an ATM terminal of an ATM network and connected to a physical layer device, a host CPU, and a host memory, said apparatus comprising:
- cell reception unit for receiving a cell from the physical layer device;
- reception VC detection unit for deciding whether the reception cell is valid according to a VPI/VCI information in a header of the reception cell;
- reception control unit for performing DMA transfer request after disassembling and error checking the cell which has been decided to be valid by the reception VC detection unit;
- reception data storage unit for temporarily storing a reception payload data extracted from the reception cell by the reception control unit;
- DMA output unit for reading out a reception payload data from the reception data storage unit according to a DMA transfer request from the reception control unit and DMA-transferring the reception payload data to the host memory;
- and
- reception clock control unit which starts clock supply to the reception control unit when the reception cell is decided to be valid by the reception VC detection unit, and terminates the clock supply to the reception control unit upon completion of processing for one cell by the reception control unit after the reception control unit performs cell disassembling and error check, stores a reception payload data in the reception data storage unit, and sends a request of a DMA transfer to the DMA output unit.
An ATM assembling/disassembling apparatus arranged on an ATM terminal of an ATM network and connected to a physical layer device, a host CPU, and a host memory, said apparatus comprising:
- transmission scheduling unit for deciding a VC for the next cell to be transmitted;
- transmission control unit for performing DMA transfer request for requesting the transmission payload data of the VC if the VC is decided to be a valid transmission VC, and according to the data fetched by the DMA transfer, creating a transmission payload data and a cell header;
- payload storage unit for temporarily storing the transmission payload data which has been created by the transmission control unit;
- transmission header storage unit for temporarily storing the cell header which has been created by the transmission control unit;
- cell assembling unit for combining the cell header stored in the transmission header storage unit and the transmission payload data stored in the transmission payload storage unit, so as to create a cell;
- cell transmission unit for transmitting the transmission cell prepared by the cell assembling unit, to the physical layer device;
- DMA input unit for reading out the transmission payload data from the host memory according to the DMA transfer request from the transmission control unit, and DMA-transferring the transmission payload data to the transmission control unit;
- and
- transmission clock control unit which starts clock supply to the transmission control unit when the transmission scheduling unit has decided to transmit a cell of the valid transmission VC and terminates the clock supply to the transmission control unit after the transmission control unit stores the cell header and the transmission payload data in the transmission header storage unit and the transmission payload storage unit, respectively, thus completing processing for one cell in the transmission control unit.
Dependencies are inferred from the claim text.