cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 87

• 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
Figure 4-4. After SAR Transmit Queue Entry Processing
28237-DSH-001-C
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 can submit partial PDUs to the CN8237. 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 CN8237 tracks the remaining
segmentation data. If a partial cell remains, the CN8237 holds the buffer until it
can complete a cell. Once the host submits an additional buffer, the CN8237
resumes segmentation.
For network management simplicity, the host can create Virtual Path VCCs (that
is, 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 CN8237 must be provided with contiguous linked SBDs that are of
the same VCC_INDEX (that is, the same VCI) for the length of the PDU. This
allows the CN8237 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 = &Z
BUFF_PNTR = &A
BUFF_PNTR = &B
BUFF_PNTR = &C
VCC_INDEX = 4
VCC_INDEX = 4
VCC_INDEX = 4
VCC_INDEX = 4
<BOM/EOM>
4.2 Segmentation Functional Description
CONTROL
CONTROL
CONTROL
CONTROL
(NULL)
<BOM>
<COM>
<EOM>
NEXT
NEXT
NEXT
NEXT
4.0 Segmentation Coprocessor
8237_031
4-7