R3721-F3210-F3171-HP High-End Firewalls Network Management Command Reference-6PW101

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loopback
Syntax
loopback { external | internal }
undo loopback
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.
Use undo loopback to disable 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 testin
g
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, 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.
Examples
# Enable internal loopback testing on GigabitEthernet 0/1.
<Sysname> system-view
[Sysname] interface gigabitethernet 0/1
[Sysname-GigabitEthernet0/1] loopback internal
port link-mode
Syntax
port link-mode { bridge | route }
undo port link-mode
View
Ethernet interface view
Default level
2: System level