[ovs-discuss] [ovn] API related questions

Murali R muralirdev at gmail.com
Mon Oct 12 18:32:04 UTC 2015

> Maybe you should explain what you are trying to accomplish.

You can imagine a sort traffic manager that will manage how to traverse a
set of destinations (lports in this case). The GBP and SFC as it stands
with neutron today are not useful for our use cases. And using OVN, not
everything can be accomplished from static configuration that is possible
now. But OVN looks like a great fit for what we need otherwise and
generally in our timeline. I am not planning to use Neutron with OVN if I
am not forced to. Currently using it for L3 and DHCP and also general
network management in the background for a quick poc which needs to work
end of this month.

Considering we can only change logical flows from northd, I may have to
look into how to modify northd to expose the kind of api needed. If you
folks can define a high level api along the lines of ofctl add-flow, it
will take quite a bit load off my shoulders :) and make OVN very useful.
One my framework is ready I can help out on ovn modules (generally external
facing) later in about 2 months.

If we need to discuss more details on use cases, we need to get into some
non-disclosures which I don't mind initiating.


On Mon, Oct 12, 2015 at 12:27 PM, Ben Pfaff <blp at nicira.com> wrote:

> On Mon, Oct 12, 2015 at 11:56:47AM -0500, Murali R wrote:
> > From the link in the previous email
> > http://openvswitch.org/pipermail/dev/2015-January/050380.html
> >
> > "Matching expressions provide a superset of OpenFlow matching
> capabilities
> > across packets in a logical datapath. Expressions use a syntax similar to
> > Boolean expressions in a programming language."
> This describes the matching syntax.  I don't see how it implies that
> users can modify flows directly.
> > I was able to use customized flows in ovs-agent to accomplish flow
> > modifications using ovs-ofctl add-flow. I was expecting we could modify
> for
> > logical flows using the ovn-northd but with logical ports. If the flow
> mods
> > can only be done from within northd, then I need to start looking into
> that
> > code. It is definitely better to have some api be exposed to define the
> > match and actions and customize flows using lports.
> The intended CMS interface to OVN is through the northbound database.
> Maybe you should explain what you are trying to accomplish.
> > When I say user, I mean a CMS.
> Understood.
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