RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
For the “Robust SN Algorithm”, the RALP makes decisions on the previous cell
based on the value of the current SN and SNP and the previous SN and SNP.
The RALP either accepts the previous cell, drops the previous cell, or inserts
cells and accepts the previous cell. The Robust SN algorithm adds delay by
requiring the following cell to arrive prior to accepting the previous cell. When a
cell is accepted, it means that the contents of the cell are available to the RFTC
for transmission onto the line. This requires that two write pointers be
maintained, one that is at the end of the last accepted cell and one at the end of
the last stored/received cell.
Inserted cells have the following properties:
• If the queue is in an unstructured mode or if the queue is in structured mode
and the inserted cell should not contain a pointer, each inserted cell contains
the number of payload bytes as determined by R_BYTES_CELL field in
R_MP_CONFIG.
• If the queue is in a structured mode and the inserted cell should contain a
pointer and R_BYTES_CELL is equal to 47, then the inserted cell contains 46
payload bytes.
• If the queue is in a structured mode and the inserted cell should contain a
pointer and R_BYTES_CELL is less than 47, then the inserted cell contains
R_BYTES_CELL payload bytes.
• If the queue is in DBCES mode and a bitmask is expected in the missing cell,
then the payload bytes will be adjusted to take into account the missing
bitmask bytes. The bitmask will be assumed to keep the same value. That is
the cell structure will be processed as if the number of active channels did not
change.
• The determination on whether or not the inserted cell should contain a pointer
is based on the pointer generation rules defined by ITU-T Recommendation
I.363.1. A pointer will be assumed if the queue is structured and the following
conditions are met:
• The SN is even AND there has been no other pointer in the group of
eight cells so far AND (the sequence number = 6 OR the structure
ends within the current inserted cell or next cell).
• If the queue is in SDF-MF mode and the inserted cell should contain signaling
data, the number of payload bytes is adjusted but the signaling information is
copied from the last valid signaling and is written to the signaling buffer.
Therefore, signaling information is frozen during the playout of the frame with
invalid signaling information.
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL
105
PMC [ PMC-SIERRA, INC ]
