PXB4219E Datasheet, PDF (59/290 Pages) Infineon Technologies AG – Interworking Element for 8 E1/T1 Lines

IWE8, V3.4
PXB 4219E, PXB 4220E, PXB 4221E
Operational Description
4.4.1.3 Sequence Number field check
This function implements the sequence number processing. It can be enabled via bit
“sn_check” in the “AAL Transmit Reference Slot”. If enabled, selection can be made
between Robust and Fast Sequence Count Algorithm as defined in the ITU-T I.363.1 [31]
by “sn_fast” in the “AAL Transmit Reference Slot”. If SN check is disabled, all cells are
accepted, no cells are discarded, lost and misinserted cells are not detected.
4.4.1.4 RTS Extraction and Verification
When the clock recovery verification is enabled (“crv_en” in the “AAL Transmit
Reference Slot”), and the port is configured for SRTS (“p_rts” = 1), RTS values are
extracted and verified.
The RTS value consists of the four CSI bits of the cells with odd SC values within a cycle
of 8 cells. A RTS value is accepted as correct if the following condition is true:
• The SN field is valid
• Four consecutive odd SC values (1, 3, 5 or 7) were received in the previous cycle of
8 cells
Otherwise the dummy RTS-value is used.
When the start of a new cycle is detected, the RTS value of the previous cycle is written
to the ICRC.
4.4.1.5 Pointer Field Detection and Verification
When SDT is enabled (“sdt” = 1 in the “AAL Transmit Reference Slot”), it is assumed that
the channel is using Structured Data Transfer. The SAR-PDU payload is supposed to be
of the P format under the following conditions:
• The SN field is valid
• Even SC value (0, 2, 4 or 6)
• The CSI field = 1
When the “sdt_once” bit in the “AAL Transmit Reference Slot” is set to 1, only the first
cell with CSI bit = 1 in a cycle of 8 cells is supposed to contain a P format SAR-SDU. The
other cells with CSI bit = 1 within the same cycle are treated as non-P format. This
operation is recommended by ITU-T I.363.1 [31]
In the cells that are supposed to contain a P format SAR-SDU, the pointer field is verified
and accepted under the following conditions:
• The parity bit is correct as defined in the ITU-T I.363.1 [31]
• The value of the offset field is between 0 and 93 or is the dummy value 127.
If an invalid pointer field (93 < pointer < 127) is detected, its content is replaced by the
dummy value (127). The SAR-SDU is processed as if it would have been received with
a dummy pointer value. The P format of the SAR-PDU payload is assumed and the first
octet of the SAR-PDU payload is not processed as user information.
Data Sheet
59
2003-01-20