RELEASED
PM7351 S/UNI-VORTEX
DATA SHEET
PMC-1980582
ISSUE 5
OCTAL SERIAL LINK MULTIPLEXER
PRESYNC period then a transition to the SYNC state is made, cell delineation is
declared and all non-idle cells with a correct HCS are passed on. In the SYNC
state synchronization is not relinquished until ALPHA consecutive incorrect HCS
patterns are found. In such an event a transition is made back to the HUNT
state. The state diagram of the cell delineation process is shown in Fig. 6.
Fig. 6: Cell delineation State Diagram
correct HCS
(bit by bit)
HUNT
Incorrect HCS
(cell by cell)
PRESYNC
ALPHA
consecutive
incorrect HCS's
(cell by cell)
DELTA
SYNC
consecutive
correct HCS's
(cell by cell)
The values of ALPHA and DELTA determine the robustness of the delineation
method. ALPHA determines the robustness against false misalignments due to
bit errors. DELTA determines the robustness against false delineation in the
synchronization process. ALPHA is chosen to be 7 and DELTA is chosen to be
6.
The loss of cell delineation (LCD) alarm is declared after 1318 consecutive cell
periods (4.0 ms at 155.52Mb/s) in the HUNT or PRESYNC states. The LCD
alarm is cleared after 1318 consecutive cells in the SYNC state.
All cells with an incorrect HCS octet are filtered out and counted. Header
correction is not performed.
9.2.4 Protection Switching Protocol
The S/UNI-VORTEX and its sister device, the S/UNI-DUPLEX inherently support
system architectures requiring fault tolerance and 1:1 redundancy of the
system’s common equipment. In point-to-point backplane architectures such as
these, the 1:1 protection also includes the associated LVDS links connecting the
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
42
PMC [ PMC-SIERRA, INC ]
