Cisco 881 inter VLAN routing via trunk port

[Philipp Philippov]

Hello my fellow network specialists an experts

I need your help

I have tried to configure inter VLAN routing on Cisco 881, but I failed.

Vlans were connected via trunk port which is connected with a switch.

Configuring Vlan interfaces doesn't work, because they are in down state as no cables are directly connected to the router.

Then I tried to configure sub interfaces on a trunk port, but there is no such option in command line.

In final, I made a conclusion that this router model does not support inter vlan routing with trunk port.

Am I right? Or there are other ways to accomplish it?

Thank you in advance.

[paolo bevilacqua]

Yes it can, create the vlan and when it comes up it will route.

[mfurnival]

It would look something like this:

SWITCH:

interface F1/0/1

switchport mode trunk

VLAN1

VLAN2

etc.

ROUTER:

interface F0/0.1

encapsulation dot1q 1

ip address 10.0.0.1 255.255.255.0

interface F0/0.2

encapsulation dot1q 2

ip address 10.0.2.1 255.255.255.0

[paolo bevilacqua]

mfurnival wrote:
It would look something like this:
SWITCH:
interface F1/0/1
switchport mode trunk
VLAN1
VLAN2 
etc.
ROUTER:
interface F0/0.1 
encapsulation dot1q 1
ip address 10.0.0.1 255.255.255.0
interface F0/0.2 
encapsulation dot1q 2
ip address 10.0.2.1 255.255.255.0

This assumes the router uses a Layer 3 interface for connecting the switch. But if it connects using a switch port, the only vlan interfaces ae configred, not subinterfaces.

[Philipp Philippov]

Thank you guys for your answers!

I found the solution:

In the configuration of VLAN interface it is required to add

no autostate

This will enable VLAN interface even if there are no ports in it, and you can ping it.