[libvirt] Notes on configuring Open vSwitch, Linux bridge and Libvirt

[Kashyap Chamarthy]

On 07/12/2013 06:30 PM, Daniel Veillard wrote:
> On Fri, Jul 12, 2013 at 05:51:14PM +0530, Kashyap Chamarthy wrote:
>> Heya Laine,
>>
>> Here's some quick notes to associate libvirt guests to Open vSwitch.
>>
>> Configure Open vSwitch
>> ----------------------
>>
>> Now that a regular Linux bridge is configured, let's try to configure an
>> OVS brdige and get IP addresses from that space:
>>
>> Create an Open vSwitch bridge device called 'ovsbr', and display the
>> current state of OpenvSwitch database contents:
>>
>>     $ ovs-vsctl add-br ovsbr
>>     $ ovs-vsctl show
>>
>>
>> Add a virtual ethernet interface called 'veth0' with
>>
>>     $ ip link add name veth0 \
>>       type veth peer name veth1
>>
>> Add 'veth0' ethernet device to the Linux bridge 'br0', and enumerate all
>> bridge devices:
>>
>>     $ brctl addif br0 veth0
>>     $ brctl show
>>
>> Now, associate virtual ethernet device 'veth1' to the OVS bridge,
>> and display the current state of OpenvSwitch database contents
>>
>>     $ ovs-vsctl add-port ovsbr veth1
>>     $ ovs-vsctl show
>>
>>
>> Bring up both the virtual ethernet interfaces 'veth0' and 'veth1'
>>
>>     $ ip link set veth0 up && \
>>       ip link set veth1 up
>>
>>
>> Update libvirt guest's bridge source to OVS
>> -------------------------------------------
>>
>> Install a minimal Fedora guest with Oz (or any other mechanism):
>>
>>     $ wget \
>>     https://github.com/kashyapc/virt-scripts/blob/master/oz/oz-jeos.bash
>>     $ ./oz-jeos f19-min f19
>>
>> Once install is finished, define the guest XML from the current dir:
>>
>>    $ virsh define f19-minJul_12_2013-12
>>
>>
>> Now let's edit libvirt's guest XML file to reflect its bridge source is
>> OVS bridge:
>>
>>     $ virsh edit f19-min
>>
>> The contents of the guest XML should reflect something along the below
>> lines:
>>
>>     $ virsh dumpxml f19-min | grep bridge -A8
>>     <interface type='bridge'>
>>       <mac address='52:54:00:a6:08:70'/>
>>       <source bridge='ovsbr'/>
>>       <virtualport type='openvswitch'>
>>         <parameters interfaceid='ecdff22d-ce80-4ae7-a008-42994415084e'/>
>>       </virtualport>
>>       <target dev='vnet2'/>
>>       <model type='virtio'/>
>>       <alias name='net0'/>
>>       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
>>     </interface>
>>
>> Start the guest, and check the IP of it:
>>
>>     $ virsh start f19-jeos --console
>>     $ ifconfig eth0
>>
>>
>> Please note, this is just a simple test, I haven't done any further experiments with VLAN
>> tagging, etc.
>>
>>
>> Slightly verbose notes:
>>
>>   http://kashyapc.fedorapeople.org/virt/openvswitch-and-libvirt-kvm.txt
>>
> 
>   Cool !
> 
> It would be good if we could get that on some permanent web
> page on libvirt.org :-)

Sure. Will submit a doc patch once I'm done with experimenting a bit with other use-cases
like pure OVS bridging, etc.


-- 
/kashyap