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

[Kashyap Chamarthy]

On 07/12/2013 05:51 PM, 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

s/Add a virtual ethernet interface called 'veth0' with/ Add a pair of virtual ethernet
interfaces 'veth0' and 'veth1'

> 
>     $ 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


It's probably worth it to make a libvirt networking docs patch.


-- 
/kashyap