# Open vSwitch with Libvirt

This document describes how to use Open vSwitch with Libvirt 0.9.11 or later. This document assumes that you followed Open vSwitch on Linux, FreeBSD and NetBSD 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

Report problems to bugs@openvswitch.org.