RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 113

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

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
5.3.1 AAL5 Processing
Figure 5-7. AAL5 EOM Cell Processing — Fields to Status Queue
28234-DSH-001-B
. . .
5.3.1.1 AAL5 COM
5.3.1.2 AAL5 EOM
ATM Cells
AAL5 PDU
Processing
Processing
(User Data)
Except for the EOM cell, all of the data within AAL5 cell payloads is user data.
The reassembly coprocessor writes all user data to memory as described in
Section
delineates the end of an AAL5 PDU.
During reassembly of the PDU, the reassembly coprocessor calculates a CRC-32
value on the received AAL5 PDU, as well as counting the length of the PDU. The
CRC-32 value is collected in an accumulator, and the LENGTH value is collected
in a Length Counter. After each received cell is processed, the reassembly
coprocessor writes the CRC-32 and LENGTH values to the reassembly VCC state
table entry for that channel.
During reassembly of the AAL5 PDU, certain bytes of the PDU other than user
data are written to a status queue entry for that PDU. The RSM coprocessor writes
these specific fields to the status queue entry:
• UU information
• the CPI field
• the LENGTH field
Figure 5-7
5.4. The EOM cell contains both user data and CPCS-PDU overhead, and
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. . .
. . .
illustrates these process functions.
EOM Cell
PAD UU CPI LENGTH CRC-32
™
5.0 Reassembly Coprocessor
5.3 CPCS-PDU Processing
Queue
Status
Entry
100074_028
5-9