ComTech: IT Support Stirling

How to configure sub-interfaces on a Cisco router

Today we are going to configure sub-interfaces on a Cisco router. We will configure the Fast Ethernet port 0/0 on a 1841 router to have two sub interfaces for vlans 1 and 2.

Hostname(config)#interface fastethernet 0/0
Hostname(config-if)#no ip address

Hostname(config)#interface fastethernet 0/0.1
Hostname(config-if)#ip address
Hostname(config-if)#encapsulation dot1q 1 native

Hostname(config)#interface fastethernet 0/0.2
Hostname(config-if)#ip address
Hostname(config-if)#encapsulation dot1q 2

Please note that the numbers at the end of the encapsulation dot1q x command indicate the vlan that the encapsulation will be active for.

About the Author


Hi I’m Chris Wakefield the owner of ComTech IT Support. I provide Windows, Mac and Linux based IT Support to small businesses in Stirling, Alloa and Falkirk.

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