Fun with QinQ tunnels - Part 2 (Routing different subnets)

From part one, we know that the purpose of a QinQ tunnel is to extend a VLAN across the WAN or network. But what if site 1 is connected to site 2 and they use different IP schemes (such as 10.1.250.0/24 and 10.100.250.0/24)? Well, making the two talk is actually very simple.

The way I have configured this is to set up a loopback interface on each side to emulate the different network, and set up routes between them. If you recall from part 1 I am using a 3550 on one side and a 3750 on the other.

We start by enabling IP routing on both sides:

3550(config)#ip routing

3750(config)#ip routing

Then we assign a virtual IP address to the VLAN:

3550(config)#int vlan 501
3550(config-if)#ip address 10.250.1.21 255.255.255.0

3750(config)#int vlan 501
3750(config-if)#ip address 10.250.1.20 255.255.255.0

And then we create our loopback interfaces to emulate the different networks:

3550(config)#interface Loopback2
3550(config-if)#ip address 10.1.250.1 255.255.255.0

3750(config)interface Loopback2
3750(config-if)#ip address 10.100.250.1 255.255.255.0

Lastly we set a routing statement with the destination network and the destination IP address, which is the virtual IP address of the vlan at the other side