5
the physical link is still down when the timer expires, the interface reports the link-down event to the upper
layers.
Link-up event suppression enables an interface to suppress link-up events and start a delay timer each
time the physical link goes up. During this delay, the interface does not report the link-up event, and the
display interface brief
or
display interface
command displays the interface state as DOWN. If the
physical link is still up when the timer expires, the interface reports the link-up event to the upper layers.
Configuring link-down event suppression
To enable an Ethernet interface to suppress link-down events:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter Ethernet interface
view.
interface
interface-type
interface-number
N/A
3.
Set a link-down event
suppression interval.
link-delay
delay-time
Link-down event suppression is disabled by
default.
Configuring link-up event suppression
To configure link-up event suppression on an Ethernet interface:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter Ethernet interface
view.
interface
interface-type
interface-number
N/A
3.
Set a link-up event
suppression interval.
link-delay
delay-time
mode up
Link-up event suppression is disabled by
default.
NOTE:
The
link-delay mode up
command and the
link-delay
command supersedes each other, and whichever is
configured last takes effect.
Configuring loopback testing on an Ethernet interface
If an Ethernet interface does not work correctly, you can enable loopback testing on it to identify the
problem. Loopback testing has the following types:
•
Internal loopback testing
—Tests all on-chip functions related to Ethernet interfaces.
•
External loopback testing
—Tests hardware of Ethernet interfaces. To perform external loopback
testing on an Ethernet interface, connect a loopback plug to the Ethernet interface. The switch sends
test packets out of the interface, which are expected to loop over the plug and back to the interface.
If the interface fails to receive any test packet, the hardware of the interface is faulty.
An Ethernet interface in a loopback test does not forward data traffic.
Configuration restrictions and guidelines
•
On an interface administratively shut down, you can perform neither internal nor external loopback
testing.