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OSN 500 550 580 V100R008C50 Alarms and Performance Events Reference 02

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The DDN_LOOP_ALM is an alarm indicating that a loopback event occur at the DDN port. If the port on the DDN side of a board is in the loopback status, the DDN_LOOP_ALM alarm is reported.


Alarm Severity Alarm Type


Equipment alarm


When you view an alarm on the network management system, select the alarm. In the Alarm Details field display the related parameters of the alarm. The alarm parameters are in the following format: Alarm Parameters (hex): parameter1 parameter2...parameterN. For details about each parameter, refer to the following table.

Name Meaning

Parameter 1

Indicates the loopback type.

  • 0x00: Inloop
  • 0x01: Outloop

Impact on the System

When the DDN_LOOP_ALM alarm occurs, some DDN port service loopback events occur in the system. Consequently, the services at the port are interrupted.

Possible Causes

The possible cause of the DDN_LOOP_ALM alarm is as follows:

The inloop or outloop at the DDN port is set manually.


  1. View the DDN_LOOP_ALM alarm on the U2000 to confirm the relevant board.
  2. After you cancel the loopback settings of the board that reports the alarm, the DDN_LOOP_ALM alarm is automatically cleared.

Related Information


Updated: 2019-01-21

Document ID: EDOC1100020975

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