Edit Mode

To enter the mode to edit timing references, you must enter the begin keyword at the config>system>sync-if-timing# prompt.

Use the following CLI syntax to enter the edit mode:

The following error message displays when the you try to modify sync-if-timing parameters without entering the keyword begin.

Configuring Timing References

Use the following CLI syntax to configure timing reference parameters. The source port specified for ref1 and ref2 is dependent on the router model type and chassis slot. Please refer to the details in the specific command descriptions.

The following displays a timing reference configuration example for the router:

Using the Revert Command

The revert command allows the clock to revert to a higher priority reference if the current reference goes offline or becomes unstable. When the failed reference becomes operational, it is eligible for selection.

When mode is non-revertive, a failed clock source is not selected again. If a node would enter holdover due to the references being in previous failed state, then the node will select one of the previously failed references rather than going into holdover.

If the current reference goes offline or becomes unstable the revert command allows the clock to revert to a higher-priority reference.

When revertive switching enabled a valid timing reference of the highest priority is used. If a reference with a higher priority becomes valid, a reference switch over to that reference is initiated. If a failure on the current reference occurs, the next highest reference takes over.

If non-revertive switching is enabled, the valid active reference always remains selected even if a higher priority reference becomes available. If the active reference becomes invalid, a reference switch over to a valid reference with the highest priority is initiated. The failed reference is eligible for selection once it becomes operational.

Other Editing Commands

Other editing commands include:

Forcing a Specific Reference

The debug sync-if-timing force-reference command should only be used to test and debug problems. Network synchronization problems may appear if network elements are left with this manual override setting. Once the system timing reference input has been forced, it may be cleared using the no force-reference command.

You can force the CPM clock to use a specific input reference using the force-reference command.

When the command is executed, the CPM clock on the active CPM immediately switches its input reference to that specified by the command. If the specified input is not available (shutdown), or in a disqualified state, the CPM clock shall use the next qualified input reference based on the selection rules.

This command also affects the BITS output port. If the BITS output port selection is set to line-reference and the reference being forced is not the BITS input port, then the system uses the forced reference to generate the signal out the BITS output port. If the BITS output port selection is set to internal-clock, then the system uses the output of the CPM clock to generate the signal for the BITS output port.

On a CPM activity switch, the force command is cleared and normal reference selection is determined.

Debug configurations are not saved between reboots.