1-4Configuring Loopback Testing on an Ethernet InterfaceYou can enable loopback testing to check whether the Ethernet interface functions properly. Note thatno data packets can be forwarded during the testing. Loopback testing falls into the following twocategories:z Internal loopback testing, which is performed within switching chips to test the functions related tothe Ethernet interfaces.z External loopback testing, which is used to test the hardware functions of an Ethernet interface. Toperform external loopback testing on an Ethernet interface, you need to install a loopback plug onthe Ethernet interface. In this case, packets sent from the interface are received by the sameinterface.Follow these steps to enable Ethernet interface loopback testing:To do… Use the command… RemarksEnter system view system-view —Enter Ethernet interface view interface interface-typeinterface-number —Enable loopback testing loopback { external | internal } OptionalDisabled by default.z As for the internal loopback test and external loopback test, if an interface is down, only the formeris available on it; if the interface is shut down, both are unavailable.z The speed, duplex, mdi, and shutdown commands are not applicable during loopback testing.z With the loopback testing enabled, the Ethernet interface operates in full duplex mode. With theloopback testing disabled, the original configurations will be restored.Enabling Auto Power Down on an Ethernet InterfaceWhen an Ethernet interface does not receive any packet for a certain period of time, it automaticallyenters the power save mode and resumes its normal state upon the arrival of a packet.Follow these steps to enable auto power down on an Ethernet interface:To do… Use the command… RemarksEnter system view system-view —EnterEthernetinterface viewinterface interface-typeinterface-numberEnterEthernetinterface viewor port groupview Enter portgroup viewport-group manualport-group-nameUse either command.If configured in Ethernetinterface view, this featuretakes effect on the current portonly; if configured in port groupview, this feature takes effecton all ports in the port group.Enable auto power down on anEthernet interface port auto-power-down RequiredDisabled by default
