H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 78)

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Configuring a loopback test
You can check whether an Ethernet port works normally by performing the Ethernet port loopback test,
during which the port cannot forward data packets normally.
Ethernet port loopback test can be one of the following types:
• Internal loopback test—Self loop is established in the switching chip to check whether there is a
chip failure related to the functions of the port.
• External loopback test—A loopback plug is used on the port. Packets forwarded by the port will be
received by itself through the loopback plug. The external loopback test can be used to check
whether there is a hardware failure on the port.
Configuration guidelines
When you configure a loopback test, follow these guidelines:
• You can perform an internal loopback test but not an external loopback test on a port that is
physically down. You can perform neither test on a port that is manually shut down.
• The system does not allow Rate, Duplex, Cable Type, and Port Status configuration on a port under
a loopback test.
• An Ethernet port operates in full duplex mode when the loopback test is performed. It restores its
original duplex mode after the loopback test.
Configuration procedure
1. From the navigation tree, select Device > Loopback.
The loopback test configuration page appears.