How to configure sub-interface or router on a stick on a L2 router

[tsabsuavyaj]

Hello,

I have a 891 router with FastEthernet0 - 7 being layer 2 and FastEthernet8 & GigabitEthernet0 being layer 3. Is it feasible to configure sub-interfaces or router on a stick on any of the L2 interfaces? If so what's the commands to achieve this?

[Reza Sharifi]

Hi,

Sub-interfaces can only be configured on layer-3 interfaces and not layer-2.

HTH
 

[tsabsuavyaj]

I was told configuring Switch Virtual Interface - SVI can achieve the same result as router on a stick?  Is that true if so how do I configure SVI?

[tsabsuavyaj]

After further research, I think this is how to configure SVI. Maybe someone can verify my configuration.

R3#conf t
R3(config)#ip routing
!
R3(config)#int f0
R3(config-if)#switchport trunk encapsulation dot1q
R3(config-if)#switchport mode trunk
R3(config-if)#exit
!
R3(config)#vlan 20
R3(config-vlan)#name SALES
R3(config-vlan)#vlan 30
R3(config-vlan)#name MARKETING
R3(config-vlan)#vlan 40
R3(config-vlan)#name LENDING
R3(config-vlan)#exit
!
R3(config)#int vlan 20
R3(config-if)#ip address 20.0.0.1 255.255.255.0
R3(config-if)#int vlan 30
R3(config-if)#ip address 30.0.0.1 255.255.255.0
R3(config-if)#int vlan 40
R3(config-if)#ip address 40.0.0.1 255.255.255.0
R3(config-if)#exit
!
R3(config)#do sh run | in vlan
vlan 20
vlan 30
vlan 40
R3(config)#