
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATMTraffic Management Device
Released
Datasheet
19
6.
The cell then is sent to the UTOPIA interface and exits the QRT on the transmit side.
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
Figure 18. QRT Data Flow Diagram
Receive UTOPIA
Cell Buffer
Receive Channel
Lookup
SSRAM
Controller
Transmit Multicast
Background
Transmit UTOPIA
Cell Buffer
Receive Queue
Controller
Transmit Queue
Controller
Receive SDRAM
Controller
Receive Switch
Cell Buffer
Transmit Switch
Cell Buffer
Transmit SDRAM
Controller
Control
SSRAM
Receive SDRAM
Cell Buffer
Transmit SDRAM
Cell Buffer
Data to QSE
Feedback from QSE
Feedback to QSE
Data from QSE
Receive UTOPIA
Level 2 Interface
Transmit UTOPIA
Level 2 Interface