RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 98

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

4.0 Segmentation Coprocessor
4.3 Segmentation Control and Data Structures
Table 4-13. Segmentation Buffer Descriptor Field Descriptions (2 of 3)
4-20
RPL_VCI
OAM_STAT
GEN_PDU
CRC10
AAL_MODE
AAL_OPT
CELL
BOM
EOM
LENGTH
GFC_DATA
Field Name
0 - The RS8234 generates the VCI field from the VCC Table Entry ATM_HEADER field.
1 - The RS8234 generates the VCI field from the NEW_VCI for all cells in the buffer. NEW_VCI will also
be copied in to the VCI portion of the ATM_HEADER field in the VCC entry.
Buffer will report status to the global OAM Status Queue SEG_CTRL(OAM_STAT_ID) instead of the
STAT specified in the VCC Table Entry.
For Message mode VCCs (VCC Table Entry STM_MODE = 0), the OAM_STAT bit of the last descriptor
for the CPCS-PDU determines which queue to use (even though the first descriptor is returned in
message mode).
See
1 - Generate AAL3/4 header and trailer, or AAL5 trailer. In AAL3/4 mode, the SAR-PDU is always
generated internally.
Overwrite last ten bits of each cell with CRC10 calculation. Used for OAM and AAL3/4 cells.
Controls AAL segmentation mode.
00 AAL5
01 AAL0—Read 48-octet ATM cell payload from segmentation buffer. Only formatting is to set PTI[0]
on last cell of an EOM buffer.
10 AAL3/4
11 Rsvd
Options for AAL_MODE:
00 Normal operation
01 SINGLE
10 Rsvd
11 Rsvd
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 AAL3/4 or 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 - RS8234 reads the 48 octet payload of ATM cells from memory and generates the ATM header
internally.
1 - The RS8234 reads the entire 52-octet ATM cell from segmentation buffer. The ATM_HEADER
stored in the VCC Table Entry is not used in this mode and AAL_MODE is ignored.
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.
For AAL_MODE = AAL0
For AAL_MODE = AAL3/4 or AAL5
Chapter 7.0
for more details.
Mindspeed Technologies
ATM ServiceSAR Plus with xBR Traffic Management
Description
Table
4-1.)
Table
™
4-1.)
28234-DSH-001-B
RS8234