PM73121ꢀAAL1gator II
Data Sheet
PMC-Sierra, Inc.
PMC-980620
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AAL1 SAR Processor
of external memory are allocated for receive queues. Since there are eight lines, each line is allo-
cated 16 kBytes of memory. This provides for 32 multiframes of E1 data (16 multiframes if T1
signaling is used) or 16 multiframes of T1 data. The queues are used in a wrap-around fashion.
Read and write pointers are used at the frame and multiframe level to access the receive queue.
Figure 34 on page 53 shows cell reception. Read and write pointers are used at the frame and mul-
tiframe level to access the correct data byte location. The RALP writes sequential cell data bytes
into successive DS0 locations assigned to that queue.
When the RALP encounters signaling bytes, it places them in the receive signaling buffer. The
buffers are organized in a multiframe format. There is one signaling nibble per multiframe allo-
cated to each DS0 channel. Therefore, 32 bytes of signaling storage are allocated for each multi-
frame worth of data buffer.
Figure 34 and the figures that follow illustrate these points and identify how different data formats
are stored in the data and signaling buffers.
R_DATA_BUFFER
Channel
17
21
31
0
0
RFTC
22
17 18 19 20 21
. . . .
. . . .
Frames
RALP reassembles bytes from
the cell. In this case, into DS0s
17 and 21.
511
Figure 34. Cell Reception
The RALP determines channels by reading from the R_CHAN_ALLOC table and then storing
the data in the corresponding timeslots of successive frame buffers in the R_DATA_BUFFER.
ꢄꢂ
PMC [ PMC-SIERRA, INC ]
