PM5347 datasheet(71/302 Pages) PMC

71 / 302 page

PM5347 S/UNI-PLUS

DATA SHEET

PMC-941033

ISSUE 6

SATURN USER NETWORK INTERFACE PLUS

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

SYNC state as described above. When both filtering and HCS checking are

enabled, cells are dropped if uncorrectable HCS errors are detected, or if the

corrected header contents match the pattern contained in the RACP Match

Header Pattern and RACP Match Header Mask registers. Idle or unassigned cell

filtering is accomplished by writing the appropriate cell header pattern into the

RACP Match Header Pattern and RACP Match Header Mask registers.

Idle/Unassigned cells are assumed to contain the all zeros pattern in the VCI and

VPI fields. The RACP Match Header Pattern and RACP Match Header Mask

registers allow filtering control over the contents of the GFC, PTI, and CLP fields

of the header.

The HCS is a CRC-8 calculation over the first 4 octets of the ATM cell header.

The RACP block verifies the received HCS using the polynomial, x8 + x2 + x + 1.

The coset polynomial, x6 + x4 + x2 + 1, is added (modulo 2) to the received HCS

octet before comparison with the calculated result. While the cell delineation

state machine (described above) is in the SYNC state, the HCS verification

circuit implements the state machine shown in Figure 6.

PM5347 Datasheet(PDF) 71 Page - PMC-Sierra, Inc