13NOTE:• For network stability, use the default or set a higher traffic polling interval.• Storm control uses a complete polling cycle to collect traffic data, and analyzes the data in the next cycle.It takes an interface at least one polling interval and at most two polling interval to take a storm controlaction.Enabling single-port loopback detection on an EthernetinterfaceIf an interface receives a packet that it sent out, a loop occurs. Loops may cause broadcast storms,degrading network performance. You can use loopback detection to detect loops on an interface andconfigure the protective action to take on the interface when a loop is detected, for example, to shutdown the interface. In addition to the configured protective action, the switch also performs other actionsto alleviate the impact of the loop condition, as described in Table 1.Table 1 Actions to take upon detection of a loop conditionActionsPort typeNo protective action is configured A protective action is configuredAccess interface• Put the interface in controlled mode.The interface discards all incomingpackets, but still forwards outgoingtraffic.• Create traps.• Delete all MAC address entries of theinterface.• Perform the configured protectiveaction.• Create traps and log messages.• Delete all MAC address entries of theinterface.Hybrid or trunkinterface• Create traps.• If loopback detection control isenabled, set the interface incontrolled mode. The interfacediscards all incoming packets, butstill forwards outgoing packets.• Delete all MAC address entries of theinterface.• Create traps and log messages.• If loopback detection control isenabled, take the configured protectiveaction on the interface.• Delete all MAC address entries of theinterface.Follow these steps to configure single-port loopback detection:To do… Use the command… RemarksEnter system view system-view —Enable global loopback detection loopback-detection enable RequiredDisabled by default.Set the loopback detection interval loopback-detection interval-timetimeOptional30 seconds by default.
