loopback

Use loopback to perform a loopback test on an Ethernet interface.

Syntax

loopback { external | internal }

Views

Ethernet interface view

Predefined user roles

network-admin

Parameters

external: Performs an external loopback test on the Ethernet interface.

internal: Performs an internal loopback test on the Ethernet interface.

Usage guidelines

If an Ethernet interface does not work correctly, you can perform a loopback test on it to identify the problem.

An Ethernet interface in a loopback test does not forward data traffic.

On an administratively shut down Ethernet interface (displayed as in ADM or Administratively DOWN state), you cannot perform an internal or external loopback test.

The speed, duplex, mdix-mode, and shutdown commands are not available during a loopback test.

During a loopback test, the Ethernet interface operates in full duplex mode. When the loopback test is complete, the port returns to its duplex setting.

Examples

# Perform an internal loopback test on Ten-GigabitEthernet 1/0/1.

<Sysname> system-view
[Sysname] interface ten-gigabitethernet 1/0/1
[Sysname-Ten-GigabitEthernet1/0/1] loopback internal
Loop internal succeeded!