cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 119

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8236
ATM ServiceSAR Plus with xBR Traffic Management
Figure 5-7. CPCS-PDU Reassembly
28236-DSH-001-B
CPCS-PDU
(For a
Specific VCC)
ATM Cells
(Hdr)
BOM Cell
(Payload)
5.3 CPCS-PDU Processing
After the VCC has been identified via channel lookup, the reassembly
coprocessor performs the appropriate CPCS-PDU processing according to the
AAL_TYPE field in the reassembly VCC table.
consecutive ATM cell payloads on a specific VCC to form a CPCS-PDU. This
processing is either reassembly into an AAL5 PDU, according to the specification
in ANSI T1.635, reassembly into an AAL3/4 PDU, or reassembly into a
transparent AAL0 PDU. The exact process is governed by the AAL type
described in detail in the subsections below.
SETUP
Each active reassembly VCC must have a corresponding entry in the reassembly
VCC table to describe its state. At channel setup time—either during system
initialization for Permanent Virtual Connections (PVCs), or dynamically for
Switched Virtual Connections (SVCs)—the host allocates a reassembly VCC
table entry and configures the VCC according to its provisioned or negotiated
characteristics. This includes the AAL in use, its assigned buffer pools and
allocation priority, and the associated segmentation VCC index
(SEG_VCC_INDEX) for full duplex connections.
OPERATION
Once the reassembly process is activated, this RSM VCC table entry is used to
track the current state of the connection and direct the CN8236 to perform
specific functions as described throughout this chapter.
The reassembly process is essentially the extraction and concatenation of
Figure 5-7
Mindspeed Technologies
illustrates the basic process function.
(Hdr)
COM Cells . . .
(Payload)
™
. . .
. . .
(Hdr)
5.0 Reassembly Coprocessor
EOM Cell
5.3 CPCS-PDU Processing
(Payload)
8236_025
5-9