cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 97

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
Table 4-9. Segmentation Buffer Descriptor Field Descriptions (2 of 2)
28237-DSH-001-C
AAL_OPT
CELL
BOM
EOM
LENGTH
GFC_DATA
WR_GFC
WR_PTI
WR_VCI
PTI_DATA
VCI_DATA
NEW_VCI
SEG_VCC_INDEX
Reserved
Field Name
Options for AAL_MODE:
For AAL_MODE = AAL0
00 = Normal operation
01 = SINGLE
10 = Reserved
11 = Reserved
For AAL_MODE = AAL5
00 = Normal operation
01 = ABORT
SINGLE: LENGTH is ignored and 48-octets are read from buffer to form the payload of a single ATM
cell. VCC table entry CRC_REM, BUFF_LENGTH, and PDU_LENGTH are not affected. By using the
LINK_HEAD bit in the transmit entry, the buffer descriptor is linked at start of buffer descriptor chain
for VCC. This means that there are no concerns with mid-cell insertion and that the cell will have low
latency. This is intended for OAM cells.
NOTE: This option MUST be set in the buffer descriptor for any Tx Queue entry with LINK_HEAD set.
To do otherwise may result in corrupted SEG data.
ABORT: Send AAL5 ABORT cell (no data is read from segmentation buffer). A buffer that has both
ABORT and BOM set is returned without sending an abort cell.
0 = CN8237 reads the 48-octet payload of ATM cells from memory and generates the ATM header internally.
1 = The CN8237 reads the entire 52-octet ATM cell from segmentation buffer. The ATM_HEADER
1 = Buffer contains the beginning of a message. (See
1 = Buffer contains the end of a message. (See
Number of bytes of data contained in the segmentation buffer. Local memory, non-EOM buffer lengths
must be multiples of 4 bytes (mod 4). Maximum allowable size is 64 KB.
Data for WR_GFC option.
0 = The CN8237 generates the GFC field from the VCC table entry ATM_HEADER field.
1 = The CN8237 overwrites the ATM header GFC field for all cells in the buffer with GFC_DATA.
Global GFC changes (active for all buffers of VCC) can be set in the VCC table entry ATM header.
This bit is active only when HEADER_MOD is set.
0 = The CN8237 generates the PTI field from the VCC table entry ATM_HEADER field.
1 = The CN8237 overwrites the ATM header PTI field for all cells in the buffer with PTI_DATA.
The host can use this feature to generate F5 and PM OAM cells. See
This bit is active only when HEADER_MOD is set.
This bit disables PM TUC and BIP16 calculations.
0 = The CN8237 generates the VCI field from the VCC table entry ATM_HEADER field.
1 = The CN8237 overwrites the ATM header VCI field for all cells in the buffer with
(0x0000|VCI_DATA). (MSBs of VCI are set to 0.)
Used to generate F4 OAM cells. (See
This bit is active only when HEADER_MOD is set.
This bit disables PM TUC and BIP16 calculations.
Data for WR_PTI option. Normally used to generate OAM cells.
Data for WR_VCI option. Normally used to generate OAM cells.
Data for the RPL_VCI. The CN8237 overwrites the VCC table entry ATM_HEADER VCI field with this
data. Therefore, the effect is permanent until the next buffer descriptor with RPL_VCI is processed.
Identifies the VCC entry in the VCC table. The CN8237 links this buffer descriptor to the identified VCC.
Always set to 0.
stored in the VCC table entry is not used in this mode and AAL_MODE is ignored.
Mindspeed Technologies
Chapter
Description
7.0.)
Table
4-1.)
Table
™
4.3 Segmentation Control and Data Structures
4-1.)
Chapter
4.0 Segmentation Coprocessor
7.0.
4-17