[ovs-discuss] Controllability of OpenFlow Controllers

[Wei-Chih Chen]

Dear Justin,

On Mon, Jul 4, 2011 at 2:38 PM, Justin Pettit <jpettit at nicira.com> wrote:

> On Jul 3, 2011, at 7:28 PM, Wei-Chih Chen wrote:
>
> > > I am using XCP (Xen Cloud Platform), which includes Open vSwitch.
> > > I would like to create virtual bridges of Open vSwitch and attach them
> to
> > > VMs on XCP.
> > > However, from the XCP community, they suggest to use OpenFlow
> controllers to
> > > control Open vSwitch instead of using ovs- commands directly because
> ovs-
> > > commands may confuse XAPI.
> > What is the difference between managing Open vSwitch by ovs- commands and
> OpenFlow controllers?
> > Can controlling through OpenFlow reach the same
> functions/purposes/results as through ovs- commands?
>
> The ovs-ofctl commands are mostly just making OpenFlow calls through a
> command line utility, so no there is really no difference.  The ovs-vsctl
> and ovs-dpctl commands configure the OVS configuration database and kernel
> modules, respectively.
>
> The XCP community was likely saying that some elements of configuration
> should be done through XAPI and others over OpenFlow.  There is some
> overlap, so doing things like adding ports to a bridge should be done
> through XAPI instead of directly with ovs-vsctl, so that XAPI doesn't get
> confused.  Internally, XAPI is making those same ovs-vsctl commands.
>
Does this mean XAPI does the same effects as what ovs-vsctl commands?
Or XAPI calls ovs-vsctl commands as its backend?

> Things that have no overlap (because XAPI has no concept of them), such as
> flow configuration must be done through done through ovs-ofctl or an
> OpenFlow controller.
>
> Products such as Citrix's DVS (Distributed Virtual Switch) make both XAPI
> and OpenFlow calls depending on what is being configured.

Does vSwitch Controller configure Open vSwitch on XenServer/XCP through
OpenFlow protocol, instead of ovs- commands?

>
> --Justin
>
>
> Thanks.

Regards,
Wayne
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