Command
Switchport Mode Trunk
Use
Enables trunking on an interface. Before enabling trunking, encapsulation needs to be set using the switchport trunk encapsulation command.
Syntax
Switch(config-if)#switchport mode trunk
Example
In this example, trunking is enabled on fa0/2. Before enabling trunking, encapsulation is also set.
SW3#conf t Enter configuration commands, one per line. End with CNTL/Z. SW3(config)#int fa0/2 SW3(config-if)#switchport trunk encapsulation dot1q SW3(config-if)#switchport mode trunk