How to Repeated Clock ID Causes the Free-Run of the NE Clock?

The ID of the internal clock source is the same as the ID of the external clock source, which results in the free-fun of the NE clock. When the setting of the internal clock source ID is cancelled, the fault is rectified.

Product

OptiX OSN 3500

Fault Type

• Time synchronization
• S1_SYN_CHANGE
• LTI

Symptom

The SL64 board is installed in both slot 8 and slot 11 of the OptiX OSN 3500. The OptiX OSN 3500 and the OptiX OSN 7500 are interconnected. The cross-connect board of each device reports the S1_SYN_CHANGE and LTI alarms.

• The clock configuration of the OptiX OSN 3500 is as follows:
  • The clock source traced by the line board is obtained from another device, and the priority of the external clock source is higher than the priority of the internal clock source.
  • The reversion mode of the high-priority clock source is set to automatic reversion.
  • The clock quality is set to Automatic Extraction.
  • Protection Status is set to Star Extended SSM Protocol.
  • The clock ID of the line board is not set.
  • The ID of the internal clock source is set to 6.
  • All the clock sources are in the normal state.

• The clock configuration of the Optix OSN 7500 is as follows:
  • The external clock source exists.
  • No clock ID for either the external clock source or the internal clock source is set.
  • The clock synchronization source is provided by the clock source of the line board with a higher priority.

Cause Analysis

The OptiX OSN 3500 and the OptiX OSN 7500 are located on the same network, and the clocks of the entire network are synchronized with the external clock source of the device outside the network. The ID of the external clock source is 6, which conflicts with the ID of the internal clock source of the Optix OSN 3500. In this case, when the OptiX OSN 3500 detects the signals of the external clock source, after checking the ID of the external source, the OptiX OSN 3500 regards the signals as the internal clock signals. Therefore, to prevent the clock tracing loop, the clock of the OptiX OSN 3500 enters the free-run mode.

Procedure

1. In the T2000 main topology, right-click the NE icon of the OptiX OSN 3500, and then choose NE Explorer.
2. Choose Configuration > Clock > Clock Subnet Configuration from the Function tree.
3. Click the Clock Subnet tab.
4. Set Internal Clock Source.
    NOTE:

   If the device does not have an external clock source, set Internal Clock Source to (None). If the ID of the internal clock source is required to be set, make sure that the ID is different from the clock IDs of other devices.
5. Click Apply. In the Operation Result dialog box, click Close.

Reference Information

None.

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