[ovs-discuss] Question on userspace ovs

[Ben Pfaff]

On Mon, Jun 01, 2015 at 05:15:07PM +0530, OVS wrote:
> I have one more query where need help, why ovs-net and br0, 2 TAP
> interfaces are created and where are they used for? I am looking right
> now for netdev type of bridge. My initial understanding was, any local
> PUNT of packet (e.g. L4 packet need to be sent to local applications)
> will go through local interface of bridge which is TAP interface. And
> by virtue of that, it will follow kernel stack for further
> processing. But i could not understand ovs-net role? Can you please
> brief on this?

The global interface (ovs-netdev, I think) is really there because the
Linux kernel needs such an interface named after the datapath, for
historical backward compatibility reasons, and we haven't bothered to
remove that for the userspace datapath because it is harmless.

> For netdev type of bridge, i guess netlink is not used, because i
> don’t see any kernel configuration needed for this case. Is my
> understanding correct?

Netlink message formatting is used internally within Open vSwitch even
in the userspace case.