Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
6. The cell then is sent to the UTOPIA interface and exits the QRT on the transmit side.
Receive SDRAM
Cell Buffer
Receive UTOPIA
Level 2 Interface
Receive UTOPIA
Cell Buffer
Receive SDRAM
Controller
Data to QSE
Receive Channel
Lookup
Receive Switch
Cell Buffer
Feedback from QSE
Feedback to QSE
Receive Queue
Controller
SSRAM
Controller
Control
SSRAM
Transmit Queue
Controller
Transmit Multicast
Background
Data from QSE
Transmit Switch
Cell Buffer
Transmit UTOPIA
Level 2 Interface
Transmit SDRAM
Controller
Transmit UTOPIA
Cell Buffer
Transmit SDRAM
Cell Buffer
Figure 18. QRT Data Flow Diagram
2.4 UTOPIA Operation
2.4.1 General
Cells received from the UTOPIA interface are first processed by the receive channel lookup block
and then queued for transmission within the receive queue controller. The cell waits in the receive
cell buffer DRAM for instruction from the receive queue controller to proceed to the switch fabric
interface.
2.4.2 UTOPIA Interface
The QRT interfaces directly to a UTOPIA interface device without needing an external FIFO. The
receive side UTOPIA has a 4-cell internal FIFO, and the transmit side contains another 4-cell
internal FIFO. The QRT UTOPIA interface is 16 bits wide and operates at frequencies up to 50
MHz. It provides the following modes:
•
•
UTOPIA Level 1 single-PHY interface
UTOPIA Level 2 multi-PHY interface
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PMC [ PMC-SIERRA, INC ]
