PXF4336 Datasheet, PDF (95/425 Pages) Infineon Technologies AG – ABM Premium ATM Buf fer Manager

3.4.5 Supervision Functions
ABM-P
PXF 4336 V1.1
Functional Description
3.4.5.1 Cell Header Protection
To guarantee that the cell header is not corrupted by the external SDRAM, it is protected
by an 8-bit interleaved parity octet. It extends over the 5-octet standard header including
the UDF1 octet. The BIP-8 octet is calculated for all incoming cells and stored at the
place of the UDF2 octet. When a cell is read out, the BIP-8 is calculated again and is
compared with the stored BIP-8. In case of a mismatch, an ’BIP8ER’ (Register 115:
ISRU, Register 116: ISRD) interrupt is generated and the cell is discarded or not,
depending on the configuration. cell header protection by BIP-8 can be disabled to
achieve UDF2 transparency.
3.4.5.2 Cell Queue Supervision
The queueing of cells in the ABM-P is implemented mostly by pointers. To detect pointer
errors, the number of the queue in which the cell is stored is appended to the cell in the
external cell storage SDRAM. When the cell is read out later, the selected queue number
is compared to the QID stored with the cell. In case of a mismatch, a ’BUFER4’ (Register
115: ISRU, Register 116: ISRD) interrupt is generated. See also “Upstream/
Downstream Cell Flow Test Registers” on Page 194.
Data Sheet
95
2001-12-17