PM5344 datasheet(39/212 Pages) PMC

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PM5344 SPTX

DATA SHEET

PMC-930531

ISSUE 6

SONET/SDH PATH TERMINATING TRANSCEIVER

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

FUNCTIONAL DESCRIPTION

9.1

Receive Path Overhead Processor

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

extraction of path overhead, extraction of the synchronous payload envelope

(virtual container), and path level alarm and performance monitoring. In tandem

path origination mode, RPOP generates an IEC based on its received path BIP-8

errors and inserts the tandem path data link. In tandem path termination mode,

RPOP accumulates incoming error counts (IEC) and extracts the tandem

connection data link. Optionally, the RPOP will overwrite the fixed stuff columns

in a tributary mapped SPE (VC) with zeros or null pointer indications in the NPI

bytes.

Diagnostic loopback of the SPTX can be enabled to connect the RPOP receive

data stream to the TRANSMIT bus interface of the Transmit Telecombus Aligner

block.

9.1.1 Pointer Interpreter

The Pointer Interpreter Block interprets the incoming pointer (H1, H2) as

specified in the references. The pointer value is used to determine the location of

the path overhead (the J1 byte) in the incoming STS-3c (AU4) or STS-1 (AU3)

stream. The algorithm can be modelled by a finite state machine. Within the

pointer interpretation algorithm three states are defined (as shown in Figure 3):

NORM_state (NORM)

AIS_state (AIS)

LOP_state (LOP)

The transition between states will be consecutive events (indications), e.g., three

consecutive AIS indications to go from the NORM_state to the AIS_state. The

kind and number of consecutive indications activating a transition is chosen such

that the behaviour is stable and insensitive to low BER. The only transition on a

single event is the one from the AIS_state to the NORM_state after receiving a

NDF enabled with a valid pointer value. It should be noted that, since the

algorithm only contains transitions based on consecutive indications, this implies

that, for example, non-consecutively received invalid indications do not activate

the transitions to the LOP_state.

PM5344 Datasheet(PDF) 39 Page - PMC-Sierra, Inc