Recently, I was working on a setup where we need to use two IP ranges for KVM guests and we found that VLAN tagging is the best way to achieve this.
Refer the below diagram for more understanding:
To allow Linux host to be aware of VLAN’s we need to enable 802.1Q tagged queuing:
We can do that using modprobe command as:
This should enable the 802.1Q tagged queuing.
To verify if it’s working you can use the command:
# lsmod | grep 8021q 8021q 21768 0
Now, we know that host can recognize VLAN’s.
Next step is to add network interfaces bind to specific VLAN in our host.
We have eno1 interface in our host and it needs to use tagged network traffic for VLAN ID 1,2.
eno1 – regular network interface
eno1.1 – virtual interface that use untagged frame from VLAN 1
eno1.2 – virtual interface that use untagged frame from VLAN 2
Now we need to configure eno1.1 interface as:
# vi /etc/sysconfig/network-scripts/ifcfg-eno1.1 In this file we write: DEVICE=eno1.1 VLAN=yes ONBOOT=yes TYPE=Ethernet
Save and Quit.
For eno1.2 perform the same steps as above.
Now we need to create a bridge interface that will allow us to bridge network VLAN1 to our guest.
To create a bridge execute the below command:
# brctl addbr br1
Now associate br1 with VLAN1 which is configured on eno1.1
# brctl addif br1 eno1.1
Now, we need to edit the configuration of our newly created bridge :
# vi /etc/sysconfig/network-scripts/ifcfg-br1 DEVICE=br1 TYPE=Bridge BOOTPROTO=none ONBOOT=yes DELAY=0
Save and quit
Now, we should associate eno1.1 to br1
# vi /etc/sysconfig/network-scripts/ifcfg-eno1.1
and we add this line:
So, now it will look like
DEVICE=eno1.1 VLAN=yes ONBOOT=yes BRIDGE=br1 TYPE=Ethernet
To apply changes in network configuration, we have to restart network service:
# /etc/init.d/network restart
That’s it, now you have successfully configured VLAN1, follow the same steps for VLAN 2.
Now, all you have to do is to assign br1 as network device to your guest machine and restart the guest machine.