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12
Default level
2: System level
Parameters
interface-type
interface-number
: Specifies an interface by its type and number.
Description
Use
interface
to enter interface view.
Examples
# Enter GigabitEthernet 1/0/1 interface view.
<Sysname> system-view
[Sysname] interface gigabitethernet 1/0/1
[Sysname-GigabitEthernet1/0/1]
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.
NOTE:
•
Enable loopback testing for troubleshooting purposes, such as identifying an Ethernet problem.
•
You cannot perform internal or external loopback testing on an administratively down (ADM DOWN)
port. On a physically down (DOWN) port, you can perform only internal loopback testing.
•
During loopback testing, the
speed
,
duplex
, 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.
Examples
# Enable internal loopback testing on GigabitEthernet 1/0/1.
<Sysname> system-view
[Sysname] interface gigabitethernet 1/0/1
[Sysname-GigabitEthernet1/0/1] loopback internal