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OSN 500 550 580 V100R008C50 Alarms and Performance Events Reference 02

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The ETHOAM_VCG_SELF_LOOP is an alarm indicating the loopback of the VCTRUNK port that runs the point-to-point OAM protocol. If the VCTRUNK port of a board receives the OAM protocol packets sent by the port or the board after detection of the loop is enabled, the alarm is reported.


Alarm Severity Alarm Type


Environment 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

The value is always 0x01.

Parameter 2, Parameter 3

Indicate the VCG port number. Parameter 2 is the higher byte, and Parameter 3 is the lower byte.

Parameter 4

Indicates the loopback reason.

  • 0x01: The port is self-looped.
  • 0x02: The board is self-looped.
  • 0x03 - 0xFF: types for expansion.

Impact on the System

In the case of the ETHOAM_VCG_SELF_LOOP alarm, the link between VCG ports is configured into a loop. The NMS provides a function of automatically shutting down the port in the case of port self-loop. If the user enables this function in advance, services at this port are interrupted. If the user does not enable this function, a broadcast storm may occur.

Possible Causes

The possible causes of the ETHOAM_VCG_SELF_LOOP alarm are as follows:

  • The links of the VCG port are configured into a loop.

  • The links between VCG ports of the board are configured into a loop.


  1. View the alarm on the NMS and determine the number of the VCG port where the alarm occurs according to alarm Parameter 2.
  2. Check the link configuration of the VCG port to see whether the transmit direction of the port is connected to the receive direction of the port. Ensure that the link configuration is correct, and then check whether the alarm is cleared.
  3. If the alarm persists, check the link configuration of the VCG port to see whether this VCG port is connected to another VCG port on the board in the transmit and receive directions. Ensure that the link configuration is correct. Then, the alarm is cleared.

Related Information


Updated: 2019-01-21

Document ID: EDOC1100020975

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