Always wanted to now how to add interfaces (VLANs or bridges) to your Linux hypervisor without dealing with the distribution specific network configuration to serve guest networks ?
Just use libvirt or its command line tool virsh to accomplish this tutorial.
First create a XML file containing your physical network layout. In this example I have a bonded Ethernet interface (bond0) and create a new Ethernet interface bond0.10 which tags the Ethernet traffic to VLAN ID 10. It is just a arbitrary number in this
example but I always suggest to tag all VM guest traffic using a bridge. Ideally those bridges are running on top a bonding interface which is sometimes called teaming. Using the Linux bonding driver you can aggregate multiple interfaces to a logical interfaces
which can enhance bandwidth. Your switch should support IEEE 802.3AD aggregation protocols like LACP otherwise I recommend to use active-passive bonding to enhance reliability against NIC or switch failures.
<interface type='bridge' name='br10'>
<start mode='onboot'/>
<bridge>
<interface type='vlan' name='bond0.10'>
<vlan tag='10'>
<interface name='bond0'/>
</vlan>
</interface>
</bridge>
</interface>
Finally create your libvirt/Linux interface
sudo virsh iface-define br10.xml
sudo virsh iface-start br10
Now adding a libvirt network using this XML file. I just create a network called vlan10 and connect it to the previous created bridge.
<network connections='1'> <name>vlan10</name> <forward mode='bridge'/> <bridge name='br10' /> </network>
Time to assemble your libvirt network.
sudo virsh net-define vlan10.xml
sudo virsh net-start vlan10
sudo virsh net-autostart vlan10
If everything is done right just check it using virsh again :
virsh # iface-list Name State MAC Address -------------------------------------------- bond0 active 00:1d:09:70:a5:a2 br10 active 00:1d:09:70:a5:a2 lo active 00:00:00:00:00:00 virsh # net-list Name State Autostart Persistent ------------------------------------------------- default active yes yes vlan10 active yes yes
virsh # net-info vlan10 Name vlan10 UUID a19fa2be-161a-f7cc-a776-e645a990eee2 Active: yes Persistent: yes Autostart: yes Bridge: br10
For the RedHat or CentOS guys who want to know how bonding interfaces can be created, just add the file ifcfg-bond0 (the number must be incremented with every new interface)
DEVICE=bond0 TYPE=Ethernet BOOTPROTO=none ONBOOT=yes BONDING_OPTS="mode=1 miimon=100"
Finally assign multiple Ethernet interfaces, at least one for mode 1 (active-passive), to this bonding device by adding the following lines in each ifcfg-ethX file:
SLAVE="yes" MASTER="bond0"
http://www.teipel.ws/2013/06/06/adding-vlans-and-bridges-using-libvirt/