RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
Figure 32 Local Loopback
RALP_FIFO
LOC_LPBK
8
From
UTOPIAI
CELL
FIFO
3
CELL
FIFO
TALP_FIFO
8
To
UTOPIAI
CELL
FIFO
9.2.2 AAL1 SAR Receive Side (RxA1SP)
9.2.2.1 RALP FIFO (RFIFO)
This block contains an 8 cell FIFO, which buffers cells received from the UTOPIA
Interface block.
Once the RUTOPIA FIFO in the UTOPIAI block has a cell to send, the UTOPIAI
polls the A1SP to determine if the RALP FIFO has room for the cell. Once the
RALP FIFO has room for the cell, the UTOPIAI reads the cell out of the
RUTOPIAI FIFO and places it in the RALP FIFO.
9.2.2.2 Receive Adaptation Layer Processor (RALP)
The RALP receives ATM cells from the RALP_FIFO and removes and checks
the AAL1 encapsulation as well as providing a VCI to queue mapping. It
performs pointer searches, detects SN mismatches, and extracts the line data
from the cells and stores it in the receive buffers located in external memory. It
also checks for overrun and underrun conditions, processes DBCES bitmasks
and checks for OAM cells The RALP does not verify the HEC because it expects
a PHY layer device to verify the HEC before presenting the cell to the AAL1gator-
8.
9.2.2.2.1 VCI Mapping
The AAL1gator-8 supports two options for VCI to queue mapping. Nine bits of
the VCI are always used. The nine-bit field can be either located in the least
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