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

[Daniel P. Berrange]

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

I don't really see why you are linking ovs to a traditional software
bridge. You now have the overheads of both bridging & ovs code in
your data path. Surely it is better to connect ovs with your physical
NIC, taking traditional bridges out of the loop completely.

Daniel
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