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A. Configuration Options
8700-A2-GB20-40 May 2002
A-15
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, System Clock Options. To access the System Clock screen,
follow this menu selection sequence:
Main Menu
→
Configuration
→
Current Configuration
→
System Clock
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.
On an LTU, the system clocks may be sourced from the DSX-1/G.703 interface
which is generating timing, or from the internal oscillator on the card (providing a
Stratum 4 reference). Typically, the primary clock source is a DSX-1/G.703 port
which is being used in a cross-connection. The LTU secondary clock sources are
restricted to G.703 ports configured for Bypass mode. On an LTU when the
system clock is configured for something other than internal, DSX-1/G.703 ports
configured for Bypass mode and internal timing will use the user-specified clock as
their reference.
On an NTU, the system clock may only be sourced from DSL ports being used in a
cross-connection. If all ports on an NTU are configured for Bypass mode, no
configuration for system clock is required (primary and secondary clock should
remain set to their default values).
main/config/system_clock
Slot: 18 Model: 87xx
SYSTEM CLOCK
System Primary Clock Reference Internal
System Secondary Clock Reference Internal
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