PM7375 datasheet(61/430 Pages) PMC

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PM7375 LASAR-155

DATA SHEET

PMC-931127

ISSUE 6

LOCAL ATM SAR & PHYSICAL LAYER

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

9.2.3 Receive Path Overhead Processor

The Receive Path Overhead Processor (RPOP) provides pointer interpretation,

extraction of path overhead, extraction of the synchronous payload envelope, path

level alarm detection (LOP, path AIS, RDI) and performance monitoring. Pointer

interpretation conforms to both Bellcore and ETSI standards.

The RPOP interprets the incoming pointer (H1, H2) as specified in the references.

Loss of pointer (LOP) in the incoming STS-3c (STM-1) or STS-1 is declared as a

result of eight consecutive invalid pointers or eight consecutive NDF enabled

indications. LOP is removed when the same valid pointer with normal NDF is

detected for three consecutive frames. Path Alarm Indication Signal (PAIS) in the

incoming STS-1/3c stream is declared after three consecutive AIS indications. PAIS

is removed when the same valid pointer with normal NDF is detected for three

consecutive frames or when a valid pointer with NDF enabled is detected. Path

Remote Defect Indication (RDI) is raise when bit 5 of the path G1 byte is set high for

five consecutive frames. Path RDI is cleared when bit 5 is low for five consecutive

frames.

Path BIP-8 calculation and verification is automatically performed with errors

accumulated into an internal saturating one second (STS-3c (STM-1) rate) counter.

Accumulation of path far end block error (FEBE) indications into an internal

saturating one second (STS-3c rate) counter is also provided.

9.3

Receive ATM Cell Processor

The Receive ATM Cell Processor (RACP) performs ATM cell delineation, provides

cell filtering based on idle/unassigned cell detection, cell filtering based on HEC

error detection, Generic Flow Control (GFC) field extraction, ATM layer alarm

detection (OCD, LCD) and performs ATM cell payload descrambling.

In addition, the number of received assigned cells is accumulated in a one second

(STS-3c/STM-1 rate) saturating counter.

9.3.1 Cell Delineation

Cell Delineation is the process of framing to ATM cell boundaries using the header

error code (HEC) field found in the cell header. The HEC is a CRC-8 calculation

over the first 4 octets of the ATM cell header. Cell delineation is performed using

the Cell Delineation State Diagram as illustrated below. ALPHA is chosen to be 7

and DELTA is chosen to be 6. These values result in a maximum average time to

delineate of 31 µs for STS-3c (STM-1) and 93 µs for STS-1. When in the HUNT

state, the RACP block asserts the out of cell delineation (OCD) alarm. If OCD

PM7375 Datasheet(PDF) 61 Page - PMC-Sierra, Inc

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