
XRT94L33
xr
Rev.1.2.0.
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
332
It will detect and flag REI-P events
It will detect and clear the UNEQ-P, PLM-P and TIM-P conditions
It will declare and clear the LOP-C and AIS-C conditions.
Finally, the Receive STS-3c POH Processor block will extract out the payload data from each incoming STS-
3c SPE, and will route this data to either the Receive ATM Cell Processor block (for ATM UNI applications) or
the Receive PPP Packet Processor block (for PPP applications).
For ATM Applications
The Receive ATM Cell Processor block will receive a continuous stream of un-framed ATM cells, and will
perform the following functions on this incoming data-stream.
Cell Delineation
HEC Byte Verification
Idle Cell Filtering
User Cell Filtering
Parity Calculation and Insertion
Afterwards, the Receive ATM Cell Processor block will route all cells (which have satisfactorily survived the
above-mentioned processing) to the Rx FIFO, within the Receive UTOPIA Interface block.
The ATM Layer Processor will read out the contents of these ATM cells via the Receive UTOPIA Interface
block of the XRT94L33.
The Receive UTOPIA Interface block provides the industry-standard ATM/PHY
interface functions.
The Receive UTOPIA Interface block will also provide signaling to support data-flow
control between the ATM Layer Processor and the Receive UTOPIA Interface block.
The Receive Section of the XRT94L33 is discussed in considerable detail below.
For PPP Applications
The Receive PPP Packet Processor block will receive a continuous stream of un-framed PPP packets, and
will perform the following functions on this incoming data-stream.
CRC-16/32 Checking
Byte-De-Stuffing
2.3.1
RECEIVE STS-3 TOH PROCESSOR BLOCK
The purpose of the Receive STS-3 TOH Processor block is to accomplish the following.
To receive an STS-3 data-stream from the remote LTE, via an Optical Transceiver or the System Back-
plane (through the Receive PECL Interface) or via the Receive STS-3 Telecom Bus Interface.
To acquire and maintain frame synchronization with the incoming STS-3 data-stream
To optionally de-scramble the incoming STS-3 data-stream.
To compute and verify the B1 and B2 bytes and increment performance monitor registers anytime it detects
B1 and B2 byte errors.
To declare and clear the following defect conditions
-
LOS (Loss of Signal)
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SEF (Severely Errored Frame)
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LOF (Loss of Frame)
-
AIS-L (Line AIS)