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5.0 Reassembly Coprocessor
5.3 CPCS-PDU Processing
RS8234
Datasheet for RS8234 xBR ServiceSAR
N8234DS1B
LI field is checked, and the following error detection and error processing
is done:
If the cell received is a BOM, and LI != 44; the SAR discards the cell,
and increments the LI_ERR counter in the VCC Head table entry.
If the cell received is a COM, and LI != 44; the SAR discards the cell,
and terminates the current CPCS-PDU. The SAR also writes a status queue
entry with the LI_ERROR bit set, the CPCS_LENGTH = 0, and
BD_PNTR pointing to the partially reassembled PDU. The SAR also
increments the LI_ERR counter in the VCC Head table entry.
If the cell received is an EOM, and (LI < 4 or LI > 44); the SAR dis-
cards the cell, and terminates the current CPCS-PDU. The SAR also writes
a status queue entry with the LI_ERROR bit set, the CPCS_LENGTH = 0,
and BD_PNTR pointing to the partially reassembled PDU. The SAR also
increments the LI_ERR counter in the VCC Head table entry.
If the cell received is an SSM, and (LI < 8 or LI > 44); the SAR dis-
cards the cell, and increments the LI_ERR counter in the VCC Head table
entry.
If the ST_EN bit in the AAL3/4 Head VCC table entry is a logic high, the
ST field in the cell is checked. The NEXT_ST field in the VCC entry is
used for this check. A value of “01” in the NEXT_ST field indicates that
the SAR was expecting a BOM/SSM cell. An “00” value indicates that the
SAR was expecting a COM/EOM cell. The following error detection and
error processing is done:
If the cell received is a BOM, and the SAR was expecting a COM or
EOM; the SAR terminates the current CPCS-PDU and writes a status
queue entry with the ST_ERROR bit set, the CPCS_LENGTH = 0, and the
BD_PNTR pointing to the partially reassembled PDU. The SAR also
increments the BOM_SSM_ERR counter in the VCC Head table entry and
starts a new CPCS-PDU with the current BOM cell.
If the cell received is an SSM, and the SAR was expecting a COM or
EOM, the SAR terminates the current CPCS-PDU and writes a status
queue entry with the ST_ERROR bit set, the CPCS_LENGTH =0, and the
BD_PNTR pointing to the partially reassembled PDU. The SAR also
increments the BOM_SSM_ERR counter in the VCC Head table entry and
processes the current cell as a valid CPCS-PDU.
If the cell received is a COM, and the SAR was expecting a BOM or
SSM, the SAR discards the cell.
If the cell received is an EOM, and the SAR was expecting a BOM or
SSM, the SAR discards the cell and increments the EOM_ERR counter in
the VCC Head table entry.
If the SN_EN bit in the AAL3/4 Head VCC table entry is a logic high, the
SN field in the cell is checked. If the cell received is COM or EOM, and
the SN field does not equal the NEXT_SN field in the VCC Table entry,
the SAR discards the cell, terminates the current CPCS-PDU, and writes a
status queue entry with the SN_ERROR bit set, CPCS_LENGTH = 0, and
the BD_PNTR pointing to the partially reassembled PDU. The SAR also
increments the SN_ERR counter in the VCC Head table entry.