Qtech QSW-8200-28T-POEAC- DC [25/85] Show loopback detection

User Manual

Chapter 3. Commands for Port Loopback Detection Function 25

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3.5 loopback-detection specified-vlan

 Command: loopback-detection specified-vlan <vlan-list>

 no loopback-detection specified-vlan [<vlan-list>]

 Function: Enable the function of loopback detection on the port and specify the VLAN

to be checked; the no operation of this command will disable the function of detecting

loopbacks through this port or the specified VLAN.

 Parameters: <vlan-list> the list of VLANs allowed passing through the port. Given the

situation of a trunk port, the specified VLANs can be checked. So this command is used

to set the vlan list to be checked.

 Default: Disable the function of detecting the loopbacks through the port.

 Command Mode: Port Mode.

 Usage Guide: If a port can be a TRUNK port of multiple Vlans, the detection of

loopbacks can be implemented on the basis of port+Vlan, which means the objects of

the detection can be the specified Vlans on a port. If the port is an ACCESS port, only

one Vlan on the port is allowed to be checked despite the fact that multiple Vlans can

be configured. This function is not supported under Port-channel.

 Example: Enable the function of loopback detection under port 1/0/2 mode.

 Switch(config)#interface ethernet 1/0/2

 Switch(Config-If-Ethernet1/0/2)#switchport mode trunk

 Switch(Config-If-Ethernet1/0/2)#switchport trunk allowed vlan all

 Switch(Config-If-Ethernet1/0/2)#loopback-detection specified-vlan 1;3;5-20

 Switch(Config-If-Ethernet1/0/2)#no loopback-detection specified-vlan 1;3;5-20

3.6 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, for example: ethernet

1/0/1.

 Command Mode: Admin and Configuration 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 1/0/4

 loopback detection config and state information in the switch!

 PortName Loopback Detection Control Mode Is Controlled

 Ethernet1/0/4 Enable Shutdown No