PM7375-SC datasheet(25/430 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

DESCRIPTION

The PM7375 LASAR-155 Local ATM Segmentation and Reassembly & Physical

Layer device is a monolithic integrated circuit that implements SONET/SDH

transmission convergence, ATM cell mapping, ATM Adaptation Layer, and PCI Bus

memory management functions for a 155.52 or 51.84 Mbit/s ATM User Network

Interface.

The LASAR-155 receives SONET/SDH frames via a bit serial interface, recovers

clock and data, and processes section, line, and path overheads. It performs

framing (A1, A2), descrambling, detects alarm conditions, and monitors section, line,

and path bit interleaved parity (B1, B2, B3), accumulating error counts at each level

for performance monitoring purposes. Line and path far end block error indications

(Z2, G1) are also accumulated. The LASAR-155 interprets the received payload

pointers (H1, H2) and extracts the synchronous payload envelope which carries the

received ATM cell payload.

The LASAR-155 frames to the ATM payload using cell delineation. Payload

descrambling, HEC single bit error correction, cell filtering based on HEC errors and

idle/unassigned cell filtering is provided. The Generic Flow Control (GFC) field is

extracted from all received cell headers and serialized out a dedicated port. Counts

of received ATM cell headers that are in error and uncorrectable, cell headers that

are errored and correctable and all passed cells are accumulated independently for

performance monitoring purposes.

The LASAR-155 supports the simultaneous reassembly and Common Part

Convergence Sublayer (CPCS) processing for 128 open Virtual Circuits (VCs). All

receive VC parameters are stored locally in the LASAR-155 device to reduce

overhead traffic on the PCI Host bus. The LASAR-155 takes all received error free

cells and passes or blocks the cell based on an open VC. Passed cells are treated

as management, control or user cells. Management and control cell payloads are

optionally checked with a CRC-10 polynomial and are optionally DMA'd to receive

ready queues in packet memory.

User cells are associated with an open VC and DMA'd to reassembly queues in

packet memory. Once a packet is reassembled and verified using a CRC-32

polynomial, the entire packet is linked into a receive ready queue. The LASAR-155

alerts the PCI Host that there are reassembled packets or cells in a receive ready

queue by asserting an interrupt on the PCI bus.

All transmit VC parameters are stored in an internal transmit parameter table to

reduce overhead traffic on the PCI bus. After a PCI Host sets up a connection using

the transmit parameter table, the PCI Host can provide packets to transmit using a

PM7375-SC Datasheet(PDF) 25 Page - PMC-Sierra, Inc

PM7375-SC Datasheet(HTML) 25 Page - PMC-Sierra, Inc

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