Cisco 15310-MA Guide de dépannage télécharger pdf (Page 120)

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Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, Release 9.0

78-18394-01

Chapter 1 General Troubleshooting

Circuits and Timing

1.11.7 Holdover Synchronization Alarm

Symptom The clock is running at a different frequency than normal and the holdover synchronization

(HLDOVRSYNC) alarm appears.

Table 1-28 describes the potential cause of the symptom and the solution.

Table 1-27 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

–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 1-28 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 2-79 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.

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