R0106-HP MSR Router Series Interface Command Reference(V7)

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loopback
Use loopback to perform a loopback test on an Ethernet interface.
Use undo loopback to cancel a loopback test on an Ethernet interface.
Syntax
loopback internal
undo loopback
Views
Ethernet interface view
Predefined user roles
network-admin
Parameters
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 a physically down interface (displayed as in DOWN state), you can perform an internal loopback test.
On an administratively shut down interface (displayed as in ADM or Administratively DOWN state), you
cannot perform an internal 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 GigabitEthernet 2/0/1.
<Sysname> system-view
[Sysname] interface gigabitethernet 2/0/1
[Sysname-GigabitEthernet2/0/1] loopback internal
port link-mode
Use port link-mode to change the link mode of an Ethernet interface.
Use undo port link-mode to restore the default.
Syntax
port link-mode { bridge | route }
undo port link-mode
Default
The following interfaces operate as Layer 2 Ethernet interfaces:
Ethernet interfaces on an SIC-4FSW, SIC-4GSW, DSIC-9FSW, HMIM-8GSW, or HMIM-24GSW
interface card.