Port Loopback Detection Troubleshooting; Port Loopback Debugging Command List - Digitalchina Networks DCS-3950 series Manual

Switch (config)#interface ethernet 0/0/1
Switch (Config-If-Ethernet0/0/1)#loopback-detection special-vlan 1-3
Switch (Config-If-Ethernet0/0/1)#loopback-detection control block

22.4 Port Loopback Detection Troubleshooting

22.4.1 Port Loopback Debugging Command List

22.4.1.1 show loopback-detection
Command：show loopback-detection [interface <interface-list>]
Function：Display the state of loopback detection on all ports if no parameter is provided,
or the state and result of the specified ports according to the parameters.
Parameters： <interface-list> the list of ports to be displayed, supporting punctuations like
';' '-'; for example: ethernet 1/1;2;5 or ethernet 1/1-6;8.
Command mode：Admin Mode.
Usage Guide：Display the state and result of loopback detection on ports with this
command.
Example：Display the state of loopback detection on port 4.
Switch(Config)# show loopback-detection interface Ethernet 1/4
loopback detection config and state information in the switch!
Ethernet 1/4
Port loopback detection: No
Port control mode: block
Is port controlled: No!
Switch(Config)#
22.4.1.2 debug loopback-detection
Command：debug loopback-detection
Function：After enabling the loopback detection debug on a port, BEBUG information will
be generated when sending, receiving messages and changing states.
Parameters：None.
Command mode：Admin Mode.
Default：Disabled by default..
Usage Guide：Display the message sending, receiving and state changes with this
command.
Example：
Switch#debug loopback-detection
%Jan 01 03:29:18 2006 Send loopback detection packet:dev Ethernet0/0/10, vlan id 1
%Jan 01 03:29:18 2006 Send loopback detection packet:dev Ethernet0/0/10, vlan id 2
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