MT92220 Zarlink Semiconductor, MT92220 Datasheet - Page 66

• Manufacturer Part Number: MT92220
• Description: 1023 Channel Voice Over IP/AAL2 Processor
• Manufacturer: Zarlink Semiconductor

66
If AAL2 CPS-packets are extracted without errors from the cells, then its CID will be looked-up in the RX AAL2 CID
Translation Structure in SDRAM. This table contains 256 entries per AAL2 VC (one entry per CID), and each entry
contains the Disassembly Structure Base Address that will be used to treat this packet in the Packet Disassembly
module. An address of 0000h indicates that packets containing this CID should be discarded. The format of the RX
AAL2 CID Translation Structure is the following:
The RX AAL2 VC structure contains many diagnostic and error reporting fields that can be used to establish traffic
characteristics on this channel. The 32-bit Transmitted Byte Count and 32-bit Transmitted Cell Count give
information on the bandwidth on this VC as well as the efficiency with which CPS-packets are being inserted into
cells.
The structure also contains 8 8-bit error counters in its structure: 3 counters for Middle HEC Error, Parity Error and
Offset > 47 Error count the cell-level errors; 3 counters for Sequence Number Error, Offset/LI Error and Straddling
HEC Error count the inter-cell errors. Finally, the Incomplete Packet Lost counter indicates how many packets
straddling 2 cells were discarded because of any of the above errors. The CID Discard Packet Received counter
indicates how many packets had an invalid entry in the CID table.
Parity Error
Offset / LI Error
CID Discard Packet
Received
Incomplete Packet Lost
Offset > 47 Error
Straddling HEC Error
Field
RX AAL2 Connection
Structure Base
+3FC
+0
b31
b30
b29
b28
b27
b26
b25
Description
This field points to the RX AAL2 Connection Structure that must be used to
process the index CID. When this field points to 0x0000, the CID is assumed
inactive and the packet is discarded. The pointer is in units of 32 bytes.
b24
This field is a counter of the number of cells received with incorrect AAL2 STF
parity.
This field is a counter of the number of cell received with an inconsistent offset
field, as compared to the expected offset field based on the LI field of the
previous CPS packet.
The field is a counter of the number of CPS packets receive on a CID that is not
assigned to a connect (i.e. that is tagged as a discard CID).
This field is a counter of the number of CPS packets lost due to partial reception
followed by an error.
This field is a counter of the number of cells received with an offset field greater
then 47.
This field is a counter of the number of HEC errors detected when a CPS header
straddled two cell.
Table 22 - Fields and Description (continued)
b23
Figure 34 - RX AAL2 CID Translation Structure
b22
Table 23 - Fields and Description
b21
b20
b19
Zarlink Semiconductor Inc.
b18
b17
b16
b15
b14
b13
CID=255, RX AAL2 Connection Structure Base [20:5]
CID=0, RX AAL2 Connection Structure Base [20:5]
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0