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Configuration Options
A-13
8700-A2-GB20-00
April 2000
System Clock
The Primary and Secondary System Clock References determine the clock used
by ports in a cross-connect configuration. For System Clock configuration
options, refer to Table A-8. To access the System Clock screen, follow this menu
selection sequence:
Main Menu →Configuration →Load Configuration From →System Clock
main/config/system_clock
Slot: 18 Model: 87xx
SYSTEM CLOCK
Primary System Clock Reference Internal
Secondary System Clock Reference Internal
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Ctrl-a to access these functions, ESC for previous menu M
ainMenu Exit
S
ave
All ports configured as system clock sources must be traceable to the same clock
reference. Ports in a cross-connect configuration that are not providing timing
themselves receive their timing from the system clock reference. All ports in a
cross-connect configuration are therefore synchronized to the system clock
reference.
The following table shows the system clock reference combinations permitted for
LTUs and NTUs. Choose the most accurate clock available for the Primary
System Clock Reference.
Device
If the Primary System Clock
Reference is . . .
The Secondary System Clock
Reference must be . . .
LTU
DSX-1 or G.703 port in
cross-connect mode
H DSX-1 or G.703 port in DS1 Bypass
mode, or
H Internal
DSX-1 or G.703 port in DS1
Bypass mode
H DSX-1 or G.703 port in DS1 Bypass
mode, or
H Internal
Internal Internal
NTU
DSL port in cross-connect mode DSL port in cross-connect mode
Internal Internal