The loopback detection function detects loops on the network connected to an interface by checking loopbacks on the interface.
A loopback occurs when packets sent from an interface are sent back to the interface. Loopbacks are usually caused by loops on the network connected to the interface, and loops cause broadcast storms.
Figure 1 Schematic diagram of loopback detection
Figure 2 Schematic diagram of loopback detection
After loopback detection is enabled on the switch periodically detects loopbacks on each Ethernet interface.
When a loopback is detected on an interface, the device switches the interface to the loopback detection state. In addition, the switch sends a trap and blocks or shuts down the interface to minimize impact on the system and the entire network caused by the loop.
