Port Loopback Detection Example - Digitalchina Networks DCS-3950 series Manual

Switch(Config-Ethernet0/0/2)#loopback-detection specified-vlan 1;3;5-20
22.2.2.3 loopback-detection interval-time
Command：loopback-detection interval-time <loopback> <no-loopback>
Function：Set the loopback detection interval.
Parameters：<loopback > the detection interval if any loopback is found, ranging from 5
to 300, in seconds.
<no-loopback > the detection interval if no loopback is found, ranging from 1 to 30, in
seconds.
Default：The default value is 30s with loopbacks existing and 10s otherwise.
Command mode：Global Mode.
Usage Guide：When there is no loopback detection, the detection interval can be
relatively shorter, for too short a time would be a disaster for the whole network if there is
any loopback. So, a relatively longer interval is recommended when loopbacks exist.
Example：Set the loopback diction interval as 35,15.
Switch(Config)#loopback-detection interval-time 35 15

22.3 Port Loopback Detection Example

As is shown in the above configuration, the switch will detect the existence of
loopbacks in the network topology. After enabling the function of loopback detection on
the port connecting the switch with the outside network, the switch will notify the
connected network about the existence of a loopback, and control the port on the switch to
guarantee the normal operation of the whole network.
The configuration task sequence of SWITCH:
Switch(config)#loopback-detection interval-time 35 15
Fig 22-1 A Typical Example of Port Loopback Detection
DCS-3950 series Ethernet switch manual
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