RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
Figure 33 Cell Header Interpretation
SHIFT_VCI=0
VP_MODE_EN=0
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9.2.2.2.2 Sequence Number Processing
When the cell is a data cell, the RALP verifies the SN CRC-3 code and parity bit.
If the SN CRC-3 and parity do not verify, the RALP attempts to correct it as
specified in ITU-T Recommendation I.363.1 and increments the
R_INCORRECT_SNP counter. If the RALP cannot correct the SN byte, it
identifies the cell as invalid.
If the DISABLE_SN bit in the R_SN_CONFIG register has been set for this
queue, then no further sequence number processing occurs. There are two
modes of sequence number processing supported: Fast Sequence Number
processing algorithm on all types of connections and Robust Sequence Number
processing on Unstructured Data Format (UDF) connections. Both the Fast and
Robust algorithms are done in accordance with the algorithms described in ITU-
T Recommendation I.363.1.
For the “Fast SN Algorithm”, the RALP acts upon the current cell based on the
value of the current SN and SNP and the previous SN and SNP. The RALP
either accepts the current cell, drops the current cell, or accepts the current cell
and inserts cells.
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