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OSN 500 550 580 V100R008C50 Alarms and Performance Events Reference 02

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The DDN_CRC4_ERR_OVER is an alarm indicating that the number of CRC4 check errors in the 2 Mbit/s services on the electrical interface side crosses the threshold. For the 2 Mbit/s services, if the accumulated number of CRC check errors per second reaches or exceeds 12000, the DDN_CRC4_ERR_OVER is reported.


Alarm Severity Alarm Type


Service alarm



Impact on the System

When the DDN_CRC4_ERR_OVER alarm occurs, the system is not affected. This alarm just shows that the quality of the transmitted E1 services is degraded.

Possible Causes

The possible causes of the DDN_CRC4_ERR_OVER alarm are as follows:

  • CRC4 check errors occur in the accessed E1 services.
  • The board hardware is faulty.


  1. View the DDN_CRC4_ERR_OVER alarm on the U2000, and then confirm the path number according to the alarm parameters.
  2. Make sure that the accessed E1 services in the path are correct and no CRC4 check errors occur. Then check whether the DDN_CRC4_ERR_OVER alarm is cleared.
  3. If the alarm persists, replace the board that generates the DDN_CRC4_ERR_OVER alarm.

Related Information


Updated: 2019-01-21

Document ID: EDOC1100020975

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