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A SONET Overview
A-12 Issue 1 December 1997
SONET Demultiplexing Procedure 1
As shown in Figure A-6, demultiplexing is the inverse of multiplexing. The
unscrambled STS-1 signal from the optical conversion stages is processed to
extract the section and line overhead and accurately locate the SPE. The next
stage processes the path overhead and demultiplexes the VTs. A standard DS3
signal will be provided to the asynchronous network after path overhead
processing. For DS1 signals, the individual DS1 VTs are then processed to extract
VT overhead and, via the VT pointer, accurately locate the DS1 SPE. Finally,
desynchronization of the DS1 SPE provides a standard DS1 signal to the
asynchronous network.
Figure A-6. SONET Demultiplexing Procedure
VTG to
VT1.5
Disinterleaver
VTG to DS1 Demultiplexer
(3 Time Slots)
Process
VT-Path OH
DS1
DS1
DS1
DS1
DS3
#1
(Nine Time Slots)
(Nine Time Slots)
#7
VTG
VTG
VTG to DS1 Demultiplexer
STS-1 #3
STS-1 #1
STS-1 #2
Maps STS-1 SPE
into a DS3
STS-1 to VTG
Demultiplexer
Process STS-1
Path OH
Maps STS-1 SPE
into 7 VTGs
Demultiplexer
Process STS-1
Path OH
Maps STS-1 SPE
STS-1 to DS3
OC-3
DS3
OC-3 to STS-1
Converts OC-3
to STS-3
Processes
Section and Line
OH
Byte
STS-3 into
3 STS-1s
Demultiplexer
Process STS-1
Path OH
(Nine Time Slots)
into a DS3
Demultiplexer
STS-1 to DS3
Disinterleaves an
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