To determine whether loops occur on a Layer 2 network, two methods are available:

1. Run the display interface brief | include up command to view traffic on all Up interfaces. If a loop occurs, the values of InUti and OutUti approximate to 100% when you run the command multiple times, which are greater than the service traffic. 

Command output upon the first query is as follows:

[HUAWEI] display interface Ethernet brief | include up InUti/OutUti: input utility/output 

utility

Interface PHY Auto-Neg Duplex Bandwidth InUti OutUti 

Trunk

GigabitEthernet0/0/1 up enable full 1000M 0.56% 0.56%
--
Command output upon the last query is as follows:
[HUAWEI] display interface Ethernet brief | include up InUti/OutUti: input utility/output
utility
Interface PHY Auto-Neg Duplex Bandwidth InUti OutUti
Trunk
GigabitEthernet0/0/1 up enable full 1000M 76% 76%

--

2. Determine whether MAC address flapping occurs on the switch.

- Run the display mac-address command. If different interfaces of the switch learn the

same MAC address, MAC address flapping occurs.

- Configure MAC address flapping detection on the switch. If MAC address flapping is

detected, the switch generates an alarm.

To configure MAC address flapping detection, use this following method.
[HUAWEI-vlan10] loop-detect eth-loop alarm-only

In V200R001 and later versions, run the following command in the system view to enable MAC address flapping detection.
[HUAWEI] mac-address flapping detection 

This function is enabled by default.

Hi m7g,

can you share if there is loop occur, how to deal with it.

Thank you.

You can configure MAC Address Flapping Detection

To configure MAC address flapping detection, use this following method.

[HUAWEI-vlan10] loop-detect eth-loop alarm-only

In V200R001 and later versions, run the following command in the system view to enable MAC address flapping detection.

[HUAWEI] mac-address flapping detection

btw - This function is enabled by default.

To quickly remove loops quickly, three methods are available:

• Remove an interface from the VLAN where a loop occurs.
• Shut down an interface on the loop.
• Remove the optical fiber or the network cable from an interface on the loop.

Thank you for sharing.

Put a "Like" if the information was useful for you, thank you for your positive feedback.

Good post, it is useful.

Thank you for sharing, very useful.

This is very useful for me! Thanks for your post!