How to configure trunk on the sub-interfaces of an Ether switch module installed in a router


Wed, 07/22/2009 - 19:56
Jun 22nd, 2009
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This example shows how to configure the FastEthernet port on an 1841 router as a trunking interface. The Cisco 1841 router has two onboard FastEthernet autosensing interfaces that support 10- or 100-Mbps connections.

The sub interface becomes fa 0/x.. For instance, fa 0/1.2 represents the sub-interface for VLAN 2. In addition, it is necessary to define the encapsulation as encapsulation dot1q vlan-id.

Hostname(config)#interface FastEthernet0/1
Hostname(config-if)#no ip address

Hostname(config-if)#no shutdown

Hostname(config)#interface FastEthernet0/1.1
Hostname(config-if)#encapsulation dot1Q 1 native
Hostname(config-if)#ip address x.x.y.y < subnet mask >

Hostname(config-if)#interface FastEthernet0/1.2
Hostname(config-if)#encapsulation dot1Q 2
Hostname(config-if)#ip address x.x.y.y < subnet mask >

Note: There is no way to setup the 1841 router to negotiate the trunk.



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