H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 171)

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Configuring loopback
You can check whether an Ethernet port works correctly by performing the Ethernet port loopback test.
During the test the port cannot correctly forward data packets.
Ethernet port loopback test can be an internal loopback test or an external loopback test.
• In an 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.
• In an external loopback test, a self-loop header is used on the port. Packets forwarded by the port
will be received by itself through the self-loop header. The external loopback test can be used to
check whether there is a hardware failure on the port.
Support of Ethernet ports for internal or external loopback test depends on the device model. For more
information, see " About the H3C Access Controllers Web-Based Configuration Guide ."
Configuration guidelines
When you perform 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, while 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, and restores its
original duplex mode after the loopback test.
Loopback operation
1. Select Device > Loopback from the navigation tree.
The loopback test configuration page appears.