loopback

Syntax

loopback { external | internal }

View

Ethernet interface view

Default level

2: System level

Parameters

external: Enables external loopback testing to test all on-chip functions related to Ethernet interfaces.

internal: Enables internal loopback testing to test the hardware of Ethernet interfaces.

Description

Use loopback to enable loopback testing on an Ethernet interface.

By default, loopback testing is disabled on Ethernet interfaces.

Enable loopback testing for troubleshooting purposes, such as identifying an Ethernet problem.

During loopback testing, the speed, duplex, mdi, and shutdown commands are not available. In addition, the port is operating in full duplex mode, regardless of its duplex configuration. After loopback testing is disabled, the duplex configuration of the port is restored.

Loopback testing is a one-time operation, and is not recorded in the configuration file.

Examples

# Enable internal loopback testing on Ethernet 1/0/1.

<Sysname> system-view
[Sysname] interface ethernet 1/0/1
[Sysname-Ethernet1/0/1] loopback internal
 Loop internal succeeded!