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Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0
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 1-25 describes the potential causes of the symptom and the solutions.
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 1-26 describes the potential cause of the symptom and the solution.
Table 1-25 ONS 15310-CL or ONS 15310-MA Switches Timing Reference
Possible Problem Solution
The optical or building integrated timing supply
(BITS) input is receiving loss of signal (LOS), loss of
frame (LOF), or AIS alarms from its timing source.
The node internal clock operates at a
Stratum 3 level of accuracy. This gives the
node a free-running synchronization accuracy
of +/–4.6 ppm and a holdover stability of less
than 255 slips in the first 24 hours or 3.7 x
10
–7
per day, including temperature.
Node free-running synchronization relies on
the Stratum 3 internal clock.
Use a higher quality Stratum 1 or Stratum 2
timing source. This results in fewer timing
slips than a lower quality Stratum 3 timing
source.
The optical or BITS input is not functioning.
Synchronization status message (SSM) is set to Don’t
Use for Synchronization (DUS).
SSM indicates a Stratum 3 or lower clock quality.
The input frequency is off by more than 15 ppm.
The input clock wanders and has more than three slips
in 30 seconds.
A bad timing reference existed for at least two
minutes.
Table 1-26 Holdover Synchronization Alarm
Possible Problem Solution
The last reference input
has failed.
The clock is running at the frequency of the last valid reference input. This
alarm is raised when the last reference input fails. See the “HLDOVRSYNC”
alarm on page 2-73 for 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.