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loopback
Description
Use the loopback command 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.
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.
Example
# Enable internal loopback testing on GigabitEthernet 1/0/1.
<Sysname> system-view
[Sysname] interface gigabitethernet 1/0/1
[Sysname-GigabitEthernet1/0/1] loopback internal
port link-mode
Description
Use the port link-mode command to change the link mode of an Ethernet interface.
Use the undo port link-mode command to restore the default.
By default, Ethernet interfaces operate in Layer 2 mode.
To meet networking requirements, you can change the link mode of a port, so it can operate as a Layer 2
Ethernet interface (in bridge mode) or Layer 3 Ethernet interface (in route mode).
When you change the link mode of an Ethernet interface, all the settings of the Ethernet interface are
restored to their defaults under the new link mode.
Related commands: port link-mode interface-list.
Syntax
port link-mode { bridge | route }
undo port link-mode
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