RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 85

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

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
Figure 4-4. After SAR Transmit Queue Entry Processing
28234-DSH-001-B
4.2.2.6 Virtual Paths
4.2.2.5 Partial PDUs
SAR WRITE
(VLD = 0)
SEG VCC Table Entry (VCC_INDEX = 4)
Transmit Queue Entry
The host may submit partial PDUs to the RS8234. In this case, the SAR transmits
the data and halts on a cell boundary. The partial PDU buffers are not required to
be aligned to a cell boundary by the host. The RS8234 tracks the remaining
segmentation data. If a partial cell remains, the RS8234 will hold the buffer until
it can complete a cell. Once the host submits an additional buffer, the RS8234
resumes segmentation.
For network management simplicity, the host can create Virtual Path VCCs
(i.e., it can segment many VCIs on one VP). The host supplies the VCI for the
ATM header within each Segmentation Buffer Descriptor (SBD). When using this
method, the RS8234 must be provided with contiguous linked SBDs that are of
the same VCC_INDEX (i.e., the same VCI) for the length of the PDU. This
allows the RS8234 to multiplex VCI messages at the PDU level. For AAL5
segmentation, the host must guarantee that SBDs are linked with PDU
multiplexing to preserve CPCS-PDU integrity.
0
CURR_DESCR
LAST_DESCR
VCC STATE
BD_PNTR
Mindspeed Technologies
™
BUFF_PNTR = &C
BUFF_PNTR = &Z
BUFF_PNTR = &A
BUFF_PNTR = &B
VCC_INDEX = 4
VCC_INDEX = 4
VCC_INDEX = 4
VCC_INDEX = 4
<BOM/EOM>
4.2 Segmentation Functional Description
CONTROL
CONTROL
CONTROL
CONTROL
(NULL)
<COM>
<BOM>
<EOM>
NEXT
NEXT
NEXT
NEXT
4.0 Segmentation Coprocessor
100074_019
4-7