When does a CE switch report an alarm after detecting MAC address flapping

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In versions earlier than V100R005C10: A CE switch reports an alarm after detecting MAC address flapping for three times. The number of times cannot be configured.
In V100R005C10 and later: By default, a CE switch reports an alarm after detecting MAC address flapping for 10 times. The number of times can be configured using the mac-address flapping detection [ security-level { low | middle | high } ] command.

Other related questions:
What to do when a MAC address flapping alarm is reported
If the alarm is reported only once, ignore it. If the alarm is reported multiple times, find the first and second interfaces where the MAC address is learned. Shut down the second interface to locate the loop. Then adjust the networking to remove the loop.

After an interface on a CE switch becomes Up during the aging time, will the switch still detect MAC address flapping during the remaining aging time
The default aging time of flapped MAC addresses is 300 seconds. You can run the error-down auto-recovery cause mac-address-flapping interval interval-value command to configure it. After the command is executed, if MAC address flapping stops and the interface becomes Up after the delay, the CE switch no longer detects MAC address flapping during the remaining aging time. This is because the aging time does not expire. If detection on MAC address flapping is required, it is recommended that the delay for an interface to automatically become Up be set greater than the aging time of flapped MAC addresses.

Does the switch support MAC-FLAPPING detection
MAC-FLAPPING detection indicates detection of MAC address flapping. The S2700 does not support any modes of MAC-FLAPPING detection. The S2750, S3700, S5700, or S6700 switch supports VLAN-based MAC-FLAPPING detection. The VLAN-based MAC-FLAPPING detection function is disabled by default. Flapping actions can be enabled through command configuration. The actions include blocking ports, blocking MAC addresses, or only reporting alarms after the flapping. For example, configure the command as follows to enable the MAC address flapping detection on VLAN10. In this detection, the action is block with 10s block duration and three attempt times. [HUAWEI] loop-detect eth-loop alarm-only [HUAWEI] vlan 10 [HUAWEI-vlan10] loop-detect eth-loop block-time 10 retry-times 3 In V200R001 and later versions, the switches support globally enabled MAC-FLAPPING detection. The configuration command is as follows: [HUAWEI] mac-address flapping detection Run the mac-address flapping detection in the system view.

Maximum number of MAC address flapping times that CE series switches can detect
The maximum number of MAC address flapping times that CE series switches can detect is 65535. When the number of flapping times is greater than 65535, the MoveNum field is still 65535 in the display mac-address flapping command output. In most cases, there is a low probability that MAC address flapping occurs many times. If the number reaches the threshold, you can run the reset mac-address flapping record command to clear the detection record on CE series switches.

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