RELEASED
PM7351 S/UNI-VORTEX
DATA SHEET
PMC-1980582
ISSUE 5
OCTAL SERIAL LINK MULTIPLEXER
Table 3 : Assigned Bit Oriented Codes
Function
Codeword (left bit
transmitted first)
Remote Defect Indication (RDI)
Loopback activate
Loopback deactivate
Remote reset activate
Remote reset deactivate
Reserved
11111111 00000000
11111111 01000000
11111111 00100000
11111111 01100000
11111111 00010000
11111111 01010000
. . .
. . .
Reserved
User Defined
. . .
11111111 00000100
11111111 01000100
. . .
User Defined
Idle Code
11111111 00111110
11111111 01111110
9.2.3 Cell Delineation Process
The S/UNI-VORTEX performs HCS cell delineation, payload descrambling, idle
cell filtering and header error detection to recover valid cells from the receive
high-speed links. These functions are performed in the spirit of ITU-T
Recommendation I.432.1, but support 9 to 13 byte cell headers.
Cell delineation is the process of framing to cell boundaries using the header
check sequence (HCS) field found in the cell header. The HCS is a CRC-8 (x8 +
x2 + x + 1) calculation over all octets of the cell header. In accordance with ITU-
T Recommendation I.432.1, the coset polynomial x6 + x4 + x2 + 1 is added
(modulo 2) to the received HCS octet before comparison with the calculated
result. When performing delineation, correct HCS calculations are assumed to
indicate cell boundaries.
The cell delineation circuitry performs a sequential bit-by-bit hunt for a correct
HCS sequence. This state is referred to as the HUNT state. When a correct
HCS is found, a particular cell boundary is assumed and the PRESYNC state is
entered. This state verifies that the previously detected HCS pattern was not a
false indication. If the HCS pattern was a false indication then an incorrect HCS
should be received within the next DELTA cells and the delineation state
machine falls back to the HUNT state. If an incorrect HCS is not found in this
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
41
PMC [ PMC-SIERRA, INC ]
