PM8621 datasheet(49/184 Pages) PMC

49 / 184 page

NSE-8G™ Standard Product Data Sheet

Preliminary

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

Document ID: PMC-2010850, Issue 1

The frame alignment state machine establishes frame alignment over the link and is based on the

frame and not the multiframe alignments. When the frame alignment state machine is in the out-

of-frame-alignment state, it maintains the current alignment, while searching for a C1FP

character. When it finds the C1FP character the state machine transitions to the in-frame-

alignment state. While in the in-frame-alignment state, the state machine monitors out-of-place

C1FP characters. Out-of-place C1FP characters are identified by maintaining a frame counter

based on the C1FP character. The counter is initialized by the C1FP character when in the out-of-

character-alignment state, and is unaffected in the in-character-alignment state. If three

consecutive C1FPs have been found that do not agree with the expected location as defined by the

frame counter, the state will change to out-of-frame-alignment state.

The frame alignment state machine is also sensitive to character alignment. When the character

alignment state machine is in the out-of-character-alignment state, the frame alignment state

machine is forced out-of-alignment, and is held in that state until the character alignment state

machine transitions to the in-character alignment state.

Figure 10 Frame Alignment State Machine

out-of-

frame-

alignment

in-frame-

alignment

3 consecutive out-of-place

C1FPs or

out-of-character alignment

Found C1FP and

not (out-of-character alignment)

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