Enabling loopback testing on an Ethernet interface
![[CAUTION: ]](images/caution.png) | CAUTION: After you enable this feature on an Ethernet interface, the interface does not forward data traffic. | |
Perform this task to determine whether an Ethernet link works correctly.
Loopback testing includes the following types:
Internal loopback testing—Tests the device where the Ethernet interface resides. The Ethernet interface sends outgoing packets back to the local device. If the device fails to receive the packets, the device fails.
External loopback testing—Tests the inter-device link. The Ethernet interface sends incoming packets back to the remote device. If the remote device fails to receive the packets, the inter-device link fails.
Configuration restrictions and guidelines
The shutdown and loopback commands are mutually exclusive.
After you enable this feature on an Ethernet interface, the Ethernet interface switches to full duplex mode. After you disable this feature, the Ethernet interface restores to its duplex setting.
Configuration procedure
To enable loopback testing on an Ethernet interface:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter Ethernet interface view. | interface interface-type interface-number | N/A |
3. Enable loopback testing. | loopback { external | internal } | By default, loopback testing on an Ethernet interface is disabled. |