Operation Manual – Port Basic ConfigurationH3C S3100 Series Ethernet Switches Chapter 1 Port Basic Configuration1-71.1.7 Enabling Loopback TestYou can configure the Ethernet port to run loopback test to check if it operates normally.The port running loopback test cannot forward data packets normally. The loopbacktest terminates automatically after a specific period.Table 1-6 Enable loopback testOperation Command RemarksEnter system view system-view —Enter Ethernet port view interface interface-typeinterface-number —Enable loopback test loopback { external | internal } OptionalNote:z external: Performs external loop test. In the external loop test, self-loop headersmust be used on the port of the switch ( for 100M port, the self-loop headers aremade from four cores of the 8-core cables, for 1000M port, the self-loop header aremade from eight cores of the 8-core cables, then the packets forwarded by the portwill be received by itself.). The external loop test can locate the hardware failures onthe port.z internal: Performs internal loop test. In the internal loop test, self loop is establishedin the switching chip to locate the chip failure which is related to the port.Note that:z After you use the shutdown command on a port, the port cannot run loopbacktest.z You cannot use the speed, duplex, mdi and shutdown commands on the portsrunning loopback test.z Some ports do not support loopback test, and corresponding prompts will be givenwhen you perform loopback test on them.1.1.8 Configuring a Port GroupTo make the configuration task easier for users, certain devices allow users to configureon a single port as well as on multiple ports in a port group. In port group view, the useronly needs to input the configuration command once on one port and that configurationwill apply to all ports in the port group. This effectively reduces redundantconfigurations.A Port group could be manually created by users. Multiple Ethernet ports can be addedto the same port group but one Ethernet port can only be added to one port group.
