XRT94L33IB-L Exar Corporation, XRT94L33IB-L Datasheet - Page 206

• Manufacturer Part Number: XRT94L33IB-L
• Description: IC MAPPER DS3/E3/STS-1 504TBGA
• Manufacturer: Exar Corporation

Specifications of XRT94L33IB-L

• Applications: Network Switches
• Interface: Bus
• Voltage - Supply: 3.14 V ~ 3.47 V
• Package / Case: 504-LBGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

XRT94L33
Rev.1.2.0.
2.2.6.13
The Transmit ATM Cell Processor block consists of a “Cell Scrambler” block.
functional block diagram of the “Transmit ATM Cell Processor block” with the “Cell Scrambler” block
highlighted.
Figure 32: Illustration of the Transmit ATM Cell Processor block Functional Block Diagram with the
“Cell Scrambler” block highlighted
If the “Cell Payload Scrambler” block is enabled, then it will scramble the payload bytes (within each outbound
ATM cell) per the polynomial x
prevent the contents of payload bytes from mimicking certain framing alignment bytes, within a given standard
transport medium. However, this rationale is not very important in SONET applications, in which all bytes
(with the exception of the A1 and A2 bytes) within the “outbound” STS-N or STS-Nc data-stream are also
scrambled.
If should be noted that the “Cell Payload Scrambler” block only scrambles the payload bytes. The “Cell
Payload Scrambler” block does not alter the value of the five (5) header bytes within each outbound ATM cell.
The user can enable the “Cell Payload Scrambler” block by setting Bit 1 (Cell Payload Scramble Enable),
within the “Transmit ATM Control – Byte 0” Register; as depicted below.
Transmit UTOPIA
T
Interface Block
HE
TxFIFO
TxFIFO
C
ELL
Main Data Path
P
AYLOAD
S
43
CRAMBLER
Generator
Checker
+ 1. Historically, the purpose of the Cell Payload Scrambler block is to
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
Generator
Checker
Parity
Idle Cell
Block
Parity
Idle Cell
Block
B
LOCK
User Cell
Calculation
HEC Byte
User Cell
Calculation
Insertion
HEC Byte
Filter
Block
Insertion
206
Filter
Block
Block
Block
&
&
Cell Extraction
Cell Insertion
Cell Extraction
Transmit GFC
Cell Insertion
Cell Payload
Processor
Processor
Transmit GFC
Nibble-Field
Cell Payload
Scrambler
Processor
Processor
Buffer/
Nibble-Field
Input Port
Buffer/
Scrambler
Buffer/
Buffer/
Input Port
Block
Block
Block
Block
Microprocessor
Figure 32 presents the
Microprocessor
STS-3c/STS-12c
Processor Block
To Transmit
Interface
Input Port
Interface
TxGFC
Block
Block
POH
xr