PM8610 Datasheet, PDF (82/338 Pages) PMC-Sierra, Inc – SBI Bus Serializer / STS-12 Time Slot Interchange

SBS Telecom Standard Product Data Sheet
Preliminary
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 3 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
3 consecutive out-of-place
C1FPs or
out-of-character alignment
out-of-
frame-
alignment
in-frame-
alignment
Found C1FP and
not (out-of-character alignment)
10.15.5 SBI336S Multiframe Alignment
SBI336S multiframe alignment is communicated across the link by controlling the frequency of
the C1FP character. The most frequent transmission of the C1FP character is every four SBI336S
frame times. This is the SBI336S multiframe and is used when there are no synchronous
tributaries requiring signalling multiframe alignment on the SBI336S bus. When there are
synchronous tributaries on the SBI336S bus the C1FP character is transmitted every 48 frame
times. This is the CAS signaling multiframe and is the lowest common multiple of the 24 frame
T1 multiframe and the 16 frame E1 multiframe.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
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Document ID: PMC-2000168, Issue 3