Help Center/ Huawei Qiankun CloudService/ More Documents/ Device Alarm Handling/ V200 LSW Alarms/ ALM-3276800217 A loop is detected in the network
Updated on 2024-01-25 GMT+08:00

ALM-3276800217 A loop is detected in the network

Description

LDT/4/DetectLoop: OID [OID] The port detected loop. (InterfaceIndex=[integer], InterfaceName=[octet], VlanListLow=[octet], VlanListHigh=[octet])

If the packets that a port sends is returned to the port through the local VLAN, it indicates the packets are looped. A loop may cause a broadcast storm.

A loop is detected.

Attribute

Alarm ID

Alarm Severity

Alarm Type

3276800217

Warning

Equipment alarm

Parameters

Name

Meaning

OID

Indicates the MIB object ID of the alarm.

hwLdtInterfaceIndex

Indicates the index of a port, that is, the index of a physical port at the link layer.

hwLdtInterfaceName

Indicates the name of a port.

hwLdtPortLoopVlanlistLow

Indicates the lower ID of the VLAN that the alarmed port belongs to. The value ranges from 0 to 2047. The value 0 is not used.

hwLdtPortLoopVlanlistHigh

Indicates the higher ID of the VLAN that the alarmed port belongs to. The value ranges from 2048 to 4095. The value 4095 is not used.

Impact on the System

Packets sent from the interface are sent back to the interface through another interface in the same VLAN. This loop may cause broadcast storms in the VLAN.

Possible Causes

The network where the device locates has a loop.

Procedure

  1. Run the display loop-detection command in the system view or interface view to check information about loop detection on the interface. The following operations are performed according to the workmode field:

    • If the value of workmode is trap, the port sends the trap and records logs without processing a detected loop. You need to clear this alarm manually. Run the display this command in the interface view to view the VLAN that the port belongs to. Then go to step 2.

    • If the value of workmode is block, the port sends the Trap alarm, records logs, blocks the port, and deletes the MAC address forwarding entry. Go to step 3.

    • If the value of workmode is nolearning, the system sends the Trap alarm, records logs, disables the port from learning MAC addresses, and keeps the normal packet forwarding function of the port. Go to step 3.

    • If the value of workmode is shutdown, the system sends the Trap alarm and records logs. The port is disabled automatically. Go to step 3.

    • If the value of workmode is quitvlan, the system sends traps and records logs, and deletes the interface from the VLAN where a loop occurs. Go to step 3.

  2. Remove the loop manually.

    Do as follows to remove the loop manually:

    • Disconnect the alarmed port manually.

      Solution:

      • Remove the connection cable on the port where the loop alarm is generated.

      • Run the shutdown command in the interface view to set the port to down state.

    • Run the loop-detection mode command to set the port to a working mode other than the Trap mode. Then the system processes the alarm automatically.

  3. Wait until the interface recovery time expires, and check whether a clear alarm is received.

    (1) If a clear alarm is received, go to step 5.

    (2) If not, go to step 4.

  4. Contact technical support personnel.
  5. End.

Related Information

None