                 How to Use Open vSwitch with Libvirt
                 ====================================

This document describes how to use Open vSwitch with Libvirt 0.9.11 or
later. The Open vSwitch support in Libvirt 0.9.11 eliminates the need to
use OVS Linux Bridge compatibility layer (brcompatd) and interface up/down
scripts. This document assumes that you followed INSTALL or installed
Open vSwitch from distribution packaging such as a .deb or .rpm. The Open
vSwitch support is included by default in Libvirt 0.9.11. Consult
www.libvirt.org for instructions on how to build the latest Libvirt, if your
Linux distribution by default comes with an older Libvirt release.

Limitations
-----------
Currently there is no Open vSwitch support for networks that are managed
by libvirt (e.g. NAT). As of now, only bridged networks are supported (those
where the user has to manually create the bridge).

Setup
-----

First, create the Open vSwitch bridge by using the ovs-vsctl utility (this
must be done with administrative privileges):

 % ovs-vsctl add-br ovsbr

Once that is done, create a VM, if necessary, and edit its Domain XML file:

 % virsh edit <vm>

Lookup in the Domain XML file the <interface> section. There should be one
such XML section for each interface the VM has.

 ...
 <interface type='network'>
  <mac address='52:54:00:71:b1:b6'/>
  <source network='default'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
 </interface>
 ...

And change it to something like this:

 ...
 <interface type='bridge'>
  <mac address='52:54:00:71:b1:b6'/>
  <source bridge='ovsbr'/>
  <virtualport type='openvswitch'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
 </interface>
 ...

The interface type must be set to "bridge". The <source> XML element
specifies to which bridge this interface will be attached to. The
<virtualport> element indicates that the bridge in <source> element is an
Open vSwitch bridge.

Then (re)start the VM and verify if the guest's vnet interface is attached to
the ovsbr bridge.

 % ovs-vsctl show

Troubleshooting
---------------
If the VM does not want to start, then try to run the libvirtd process either
from the terminal, so that all errors are printed in console, or inspect
Libvirt/Open vSwitch log files for possible root cause.

Bug Reporting
-------------

Please report problems to bugs@openvswitch.org.
