Trunking Command List

Trunking Command List

The following table lists important commands for configuring and monitoring trunking on a switch.

Command	Function
Switch(config-if)#switchport mode trunk	Enables trunking on the interface. The port will not use DTP on the interface.
Switch(config-if)#switchport trunk encapsulation dot1q Switch(config-if)#switchport trunk encapsulation isl	Sets the trunking protocol Because 2960 switches only support 802.1Q, you will not use this command on 2960 switches
Switch(config-if)#switchport mode dynamic auto	Enables automatic trunking discovery and configuration. The switch uses DTP to configure trunking.
Switch(config-if)#switchport mode dynamic desirable	Enables dynamic trunking configuration. If a switch is connected, it will attempt to use the desired trunking protocol (802.1Q for 2960 switches). If a switch is not connected, it will communicate as a normal port.
Switch(config-if)#switchport mode access	Disables trunking configuration on the port.
Switch#show interface trunk Switch#show interface fa0/1 trunk	Shows interface trunking information with the following: Mode Encapsulation Trunking status VLAN assignments

Note: Two switches both configured to use desirable dynamic trunking will not trunk. At least one of the switches must be set to manually trunk or to use auto dynamic trunking.

 

 

Credit: Testout 640-802 CCNA Notes