PM5351 datasheet(89/393 Pages) PMC

89 / 393 page

S/UNI-TETRA

PMC-Sierra, Inc.

PM5351 S/UNI-TETRA

DATASHEET

PMC-1971240

ISSUE 7

SATURN USER NETWORK INTERFACE (155-TETRA)

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

'Detection Mode' state or HCS bit errors detected but not corrected while the

state machine is in the 'Correction Mode' state. The 19-bit receive cell counter

counts all cells written into the receive FIFO. Filtered cells are not counted.

Each counter may be read through the microprocessor interface. Circuitry is

provided to latch these counters so that their values can be read while

simultaneously resetting the internal counters to 0 or 1, if appropriate, so that a

new period of accumulation can begin without loss of any events. It is intended

that the counter be polled at least once per second so as not to miss HCS error

events.

10.7 Receive POS Frame Processor (RXFP)

The Receive POS Frame Processor (RXFP) performs packet extraction, provides

FCS error correction, performs packet payload de-scrambling, and provides

performance monitoring functions. The RXFP also provides a 256 byte deep

receive FIFO. This FIFO is used to separate the STS-3c (STM-1) line timing

from the link layer system timing, and to handle timing differences caused by the

removal of escape characters.

10.7.1 Overhead Removal

The overhead removal consist of striping SONET/SDH overhead bytes from the

data stream. Once overhead bytes are removed, the data stream consists of

POS frame octets which can be fed directly to the descrambler or the POS

Frame Delineation block.

10.7.2 Descrambler

When enabled, the self-synchronous descrambler operates on the POS Frame

data, de-scrambling the data with the polynomial x43 + 1. De-scrambling is

performed on the raw data stream, before any POS frame delineation or byte

destuffing is performed. Data scrambling can provide for a more robust system

preventing the injection of hostile patterns into the data stream.

10.7.3 POS Frame Delineation

This block accepts data one byte at a time and arranges it as POS framed octets.

Frame boundaries are found by searching for the Flag Character (0x7E). Flags

are also used to fill inter-packet spacing. This block removes the Flag Sequence

and passes the data onto the Byte Destuffing block.

PM5351 Datasheet(PDF) 89 Page - PMC-Sierra, Inc