Operation Manual – Port Basic ConfigurationH3C S5600 Series Ethernet Switches Chapter 1 Port Basic Configuration1-7Note:z external: Performs external loop test. In the external loop test, self-loop headersmust be used on the port of the switch (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.After you use the shutdown command on a port, the port cannot run loopback test. Youcannot use the speed, duplex, mdi and shutdown commands on the ports runningloopback test. Some ports do not support loopback test, and corresponding promptswill be given when you perform loopback test on them.1.1.8 Enabling the System to Test Connected CableYou can enable the system to test the cable connected to a specific port. The test resultwill be returned in five seconds. The system can test these attributes of the cable:Receive and transmit directions (RX and TX), short circuit/open circuit or not, the lengthof the faulty cable.Follow these steps to enable the system to test connected cables:To do... Use the command... RemarksEnter system view system-view —Enter Ethernet port view interface interface-typeinterface-number —Enable the system to testconnected cables virtual-cable-test RequiredNote:z Optical port (including Combo optical port) does not support VCT(virtual-cable-test) function.z Combo electrical port supports VCT function only when it is in UP condition (usingundo shutdown command), normal Ethernet electrical port always supports thisfunction.
