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
- 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.
-
- Remove the loop manually.
Do as follows to remove the loop manually:
- 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.
- Contact technical support personnel.
- End.
Related Information
None
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