TP-Link T1600G-18TS Configuration Manual page 118

Managing Physical Interfaces
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The following example shows how to enable loopback detection globally (keeping the
default parameters):
Switch#configure
loopback-detection interval interval-time
Set the interval of sending loopback detection packets which is used to detect the loops in
the network.
The interval of sending loopback detection packets. The valid values are from
interval-time:
1 to 1000 seconds. By default, the value is 30 seconds.
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.
: It is integral times of detection interval, ranging from 1 to 100. The default
recovery-time
value is 3.
interface { fastEthernet port | range fastEthernet port-list | gigabitEthernet port | range
gigabitEthernet port-list }
Enter interface configuration mode.
loopback-detection
Enable loopback detection of the port. By default, it is disabled.
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
port to normal status.
show loopback-detection global
Verify the global configuration of Loopback Detection.
show loopback-detection interface { fastEthernet port | gigabitEthernet port }
Verify the Loopback Detection configuration of the specified port.
end
Return to privileged EXEC mode.
copy running-config startup-config
Save the settings in the configuration file.
under interface configuration mode to recover the blocked
Loopback Detection Configuration
Configuration Guide 95