Managing Physical Interfaces
Loopback Detection Configuration
Configuration Guide
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Step 3
loopback-detection interval
interval-time
Set the interval of sending loopback detection packets which is used to detect the loops in
the network.
interval-time
:
The interval of sending loopback detection packets. The valid values are from
1 to 1000 seconds. By default, the value is 30 seconds.
Step 4
loopback-detection recovery-time
recovery-time
Set the recovery time, after which the blocked port in Auto Recovery mode can
automatically recover to normal status.
recovery-time
: It is integral times of detection interval, ranging from 1 to 100. The default
value is 3.
Step 5
interface {
fastEthernet
port
|
range fastEthernet
port-list
|
gigabitEthernet
port
|
range
gigabitEthernet
port-list
}
Enter interface configuration mode.
Step 6
loopback-detection
Enable loopback detection of the port. By default, it is disabled.
Step 7
loopback-detection config process-mode {
alert | port-based
} recovery-mode {
auto |
manual
}
Set the process mode when a loopback is detected on the port. There are two modes:
alert
:
When a loop is detected, the switch will send a trap message and generate an entry on
the log file. It is the default setting.
port-based
: When a loop is detected, the switch will send a trap message and generate an
entry on the log file. In addition, the switch will totally block the port on which the loop is
detected and no packets can pass through the port.
Set the recovery mode for the blocked port. There are two modes:
auto
: After the recovery time, the blocked port will automatically recover to normal status
and restart to detect loops in the network.
manual
: The blocked port can only be released manually. You can use the command
loopback-detection recover
under interface configuration mode to recover the blocked
port to normal status.
Step 9
show loopback-detection global
Verify the global configuration of Loopback Detection.
Step 10
show loopback-detection interface {
fastEthernet
port
|
gigabitEthernet
port
}
Verify the Loopback Detection configuration of the specified port.
Step 11
end
Return to privileged EXEC mode.
Step 12
copy running-config startup-config
Save the settings in the configuration file.
The following example shows how to enable loopback detection globally (keeping the
default parameters):
Switch#configure
