VSC6134
Datasheet
row number for the framer output data (counting from 0 to 8 = 9 rows per SONET frame and 0 to 3 in
ODU/OTU frame). The output COLCNT signal indicates the column number for the framer output data.
COLCNT counts from 0 to 89 = 90 column per row in SONET mode and, 0 to 509 = 510 column per
row in OTU and 0 to 477 = 478 column per row in ODU, for 64 bit wide data bus.The output SET-CNT
signal counts from 0 to 23 = 24 per column in SONET mode and remains inactive in ODU/OTU mode.
The framer state machine (FSM) is shown in the following figure.
Figure 31. FSM State Machine for OOF
IN FRAME
(FRAME M DETECT)
Next
Framing pattern not found
atter a frame period
FRAME2 DETECT
Framing pattern found errored in N
(provisonable) consecutive frames
Next
Framing pattern found
after one Frame Period
Framing pattern not found
after frame period
FRAME1 DETECT
OOF = 1
Framing pattern found
at t = 0
RESET
On reset, the frame aligner goes into an out of frame (OOF) state with both the SEF (severely errored
frame) and LOF (loss of frame) alarms active. The framer then searches for the framing pattern. Two
control bits, FRAMECTRL [1:0], are used to select the framing pattern as shown in the following table.
Table 57. Framing Pattern for FRAMECTRL[1:0]
FRAMECTRL[1:0]
Framing Pattern
A1A2
00
01
10
11
A1A2A2
A1A1A2A2
Reserved
The frame aligner goes into IN FRAME if it finds M consecutive valid framing patterns (see Table 58,
page 142) spaced out in time by one frame period, which varies for SONET/ODU/OTU mode. On the
first occurrence of the valid framing pattern, the FSM enters the FRAME DETECT state and
synchronizes its timing to the detected frame boundary. The FSM enters FRAME2 DETECT state when
the framing pattern is found for the second time in correct position. The FSM continues searching until
the framing pattern is found M consecutive times (including FRAME2 DETECT state), in which case
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VMDS-10185 Revision 4.0
July 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
