Cisco Systems manual ONS 15310-CL or ONS 15310-MA Switches Timing Reference

Chapter 1 General Troubleshooting

1.10.6 ONS 15310-CL or ONS 15310-MA Switches Timing Reference

1.10.6 ONS 15310-CL or ONS 15310-MA Switches Timing Reference

Symptom Timing references switch when one or more problems occur.

Table 1-25describes the potential causes of the symptom and the solutions.

Table 1-25 ONS 15310-CL or ONS 15310-MA Switches Timing Reference

Possible Problem	Solution
The optical or building integrated timing supply	The node internal clock operates at a
(BITS) input is receiving loss of signal (LOS), loss of	Stratum 3 level of accuracy. This gives the
frame (LOF), or AIS alarms from its timing source.	node a free-running synchronization accuracy
	of +/–4.6 ppm and a holdover stability of less
The optical or BITS input is not functioning.
	than 255 slips in the first 24 hours or 3.7 x
Synchronization status message (SSM) is set to Don’t
	10–7per day, including temperature.
Use for Synchronization (DUS).	Node free-running synchronization relies on
SSM indicates a Stratum 3 or lower clock quality.
	the Stratum 3 internal clock.
The input frequency is off by more than 15 ppm.	Use a higher quality Stratum 1 or Stratum 2
The input clock wanders and has more than three slips	timing source. This results in fewer timing
in 30 seconds.	slips than a lower quality Stratum 3 timing
	source.
A bad timing reference existed for at least two
minutes.

1.10.7 Holdover Synchronization Alarm

Symptom The clock is running at a different frequency than normal and the holdover synchronization (HLDOVRSYNC) alarm appears.

Table 1-26describes the potential cause of the symptom and the solution.

Table 1-26 Holdover Synchronization Alarm

Possible Problem	Solution
The last reference input	The clock is running at the frequency of the last valid reference input. This
has failed.	alarm is raised when the last reference input fails. See the “HLDOVRSYNC”
	alarm on page 2-73for a detailed description of this alarm.
	Note The ONS 15310-CL and ONS 15310-MA support holdover timing
	per Telcordia GR-4436 when provisioned for external (BITS)
	timing.

Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0

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