Holdover Synchronization Alarm - Cisco ONS 15454 DWDM Manual

1.8.1 ONS 15454 Switches Timing Reference
1.8.1 ONS 15454 Switches Timing Reference
Symptom

1.8.2 Holdover Synchronization Alarm

Symptom
appears.
Note
Cisco ONS 15454 DWDM Troubleshooting Guide, R7.0.1
1-52
Timing references switch when one or more problems occur.
The optical or building integrated timing supply (BITS) input is receiving loss of
Possible Cause
signal (LOS), loss of frame (LOF), or AIS alarms from its timing source.
The optical or BITS input is not functioning.
Possible Cause
The synchronization status messaging (SSM) message is set to do not use for
Possible Cause
synchronization (DUS).
SSM indicates a Stratum 3 or lower clock quality.
Possible Cause
The input frequency is off by more than 15 ppm.
Possible Cause
The input clock wanders and has more than three slips in 30 seconds.
Possible Cause
A bad timing reference existed for at least two minutes.
Possible Cause
Recommended Action The ONS 15454 internal clock operates at a Stratum 3E level of accuracy. This
gives the ONS 15454 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
ONS 15454 free-running synchronization relies on the Stratum 3 internal clock. Over an extended
time period, using a higher quality Stratum 1 or Stratum 2 timing source results in fewer timing slips
than a lower quality Stratum 3 timing source.
The clock is running at a different frequency than normal and the
The last reference input has failed.
Possible Cause
The clock is running at the frequency of the last known-good reference input.
Recommended Action
This alarm is raised when the last reference input fails. See the
page 2-65 for a detailed description.
The ONS 15454 supports holdover timing per Telcordia GR-436 when provisioned for external
(BITS) timing.
Chapter 1 General Troubleshooting
–7
/day, including temperature.
"HLDOVRSYNC" alarm
"HLDOVRSYNC" alarm on
78-17742-02