the log shows that the interface which connects to the PC flapping.
1. confirmed with the customer, the port that frequently generates the alarm is connected to the PC terminal. It is suspected that the cable is physically faulty, causing the port to frequently flap. If the cable is physically faulty, there should be a CRC error packet, check the port information, and no error packet is found.
2. On-site investigation, found that the laptop is connected to the switch, and the energy-saving mode is enabled.
3. Check that the laptop NIC is set to allow the computer to turn off the device to save power. After turn off this option (Control Panel - Device Manager - Expand Network Adapter, right click on NIC, select "Properties", switch to " Power Management tab, then remove the check box before "Allow the computer to turn off this device to save power"), it becomes normal.
The laptop NIC is set to allow the computer to turn off the device to save power. In the case of enabling the power-save mode, the NIC is frequently shut down and restarted, causing the uplink switch port to flip.
Turn off Allow the computer to turn off this device to conserve power (Control Panel - Device Manager - Expand Network Adapter, right click on the NIC, select "Properties", switch to the "Power Management" tab, and then "Allow the computer to shut down this device" Remove the hook before saving power")