Paradyne U8777, 8779 manual System Clock

A. Configuration Options

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

main/config/system_clock
Slot: 18	Model: 87xx
SYSTEM CLOCK
System Primary Clock Reference	Internal
System Secondary Clock Reference	Internal

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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).

8700-A2-GB20-40 May 2002 A-15