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Alarm Handling

AR100, AR120, AR160, AR1200, AR2200, AR3200, and AR3600 V300R003

This document provides the trap description, attributes, parameters, impact on the system, possible causes, procedures, and references. This document provides a complete set of traps, through which intended readers are kept of the running status of the device so as to locate faults.

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MSTP_1. hwMstpProLoopbackDetected

MSTP_1. hwMstpProLoopbackDetected


MSTP/4/PROLBDETECTGED:OID [OID] The MSTP Process's Port has been set to discarding state because of detecting loopback. (ProcessID=[INTEGER], InstanceID=[INTEGER], PortID1=[INTEGER], PortID2=[INTEGER], PortID3=[INTEGER], PortID4=[INTEGER], PortIDFlag=[INTEGER], IfIndex=[INTEGER], PortState=[INTEGER], PortName=[STRING])

When port detected loopback, block the port and arise trap.


Alarm ID Alarm Severity Alarm Type Warning communicationsAlarm(2)


Name Meaning


Indicates the MIB object ID of the alarm.


Indicates the MSTP process ID


Indicates the instance ID.


Indicates ID 1 of the port in the MSTP process.


Indicates ID 2 of the port in the MSTP process.


Indicates ID 3 of the port in the MSTP process.


Indicates ID 4 of the port in the MSTP process.


Indicates the port flag.


Indicates the port index.


Indicates the port state.


Indicates the port name.

Impact on the System

After detecting a port blocked by local loopback, the system considers that a network storm occurs and blocks the local port to prevent the network storm from affecting services of the entire network. Services on the block port will be interrupted.

Possible Causes

When the STP port of the equipment receiving BPDU with the same designated bridge ID and designated port ID as this equipment and port, STP blocks this port and arises this trap for loopback detection will lead loop.


  1. Check whether the port where the alarm is generated is configured with local loopback.

    • If so, go to Step 4.

    • If not, go to Step 2.

  2. Check whether there is a loop formed by a hub and devices, one of which is connected to the port.

    • If so, go to Step 5.

    • If not, go to Step 3.

  3. Collect alarm information and configuration information, and then contact technical support personnel.
  4. Delete the local loopback configuration to solve the problem.
  5. Remove the self-loop network cable from the hub to solve the problem.
  6. End.

Related Information


Updated: 2019-03-06

Document ID: EDOC1100041475

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