
MT90503
Data Sheet
75
Zarlink Semiconductor Inc.
five MSBs select a number of multiframes and the five LSBs a number of frames. In strict muliframing, the five LSBs
are always set to '00000'; they can be any value in FASTCAS.
Setting the multiframing standard in the circuit emulation (CE) field will change the way the information is read from
the TDM circular buffers, as well as the standard that is used to interpret the p-byte. In addition, setting the CE bits
to a CAS setting will indicate to the RX_ SAR that CAS signalling bits should be expected at the end of the AAL1
structure.
The payload size represents the number of TDM bytes in the cell and does not include pointer or AAL1-bytes.
4.4.3 Errors
Within the four categories of errors, there are eleven possible errors. All but slip errors (overruns and underruns)
pertain only to AAL1 cells.
For the following errors, the only action taken is the generation of an error report structure (Section 4.4.4):
CRC errors
CRC/sequence number parity errors
multiple cell loss
p-byte parity
Format
TDM Bytes
Bytes Transmitted
Payload Size
AAL1 with pointer, non-p-type cell
AAL1 with pointer, p-type cell
CBR-AAL0
16
16
16
17
18
16
16
16
16
Table 24 - Payload Sizes for Various Cell Formats
Category
Error
Coverage
Example
AAL1 Byte
CRC error
CRC/Sequence
Number Parity error
Single cell loss
AAL1 cells
AAL1 cells
CSI = 1, CRC = 010, Seq. num = 110, parity bit = 1.
Even parity not observed: a parity error has occurred.
Sequence numbers 1, 2, 4 received. Cell 3 has been
lost
Sequence numbers 1, 2, 4, 3 received. A cell
misinsertion has occurred
Sequence numbers 1, 2, 5 received. Cells 3, 4 have
been lost.
P-byte = 0100110, parity bit = 0. Even parity not
observed: a p-byte parity error has occurred
P-byte received = 0x52, Structure length for that VC =
0x18. P-byte is too large
P-byte is 0x15 when 0x17 was expected.
Cell
loss/misinsertion
AAL1 cells
cell misinsertion
AAL1 cells
Multiple cell loss
AAL1 cells
P-byte errors
P-byte parity error
AAL1 cells
P-byte out-of-range
AAL1 cells
P-byte framing error
P-byte absent
Overrun
Underrun
AAL1 cells
AAL1 cells
all cells
all cells
Slip errors
See Figure 31.
See Figure 31.
Table 25 - RX_SAR errors