[ovs-discuss] Flow difference between ovs-ofctl dump-flows & ovs-dpctl dump-flows

Bhargav Bhikkaji bhargav.ietf at gmail.com
Fri Apr 25 22:46:34 UTC 2014


Ben,

Let me step back a bit.

There are 2 kinds of flows as described in FAQ. 1) OF Flows 2) Kernel flows.

As i understand,
- Kernel flows are the normal L2 flows that are learnt on the fly by
datapath.
- OF flows are the one programmed by controller or using ovs-ofctl.

Assume a case where "ovs-ofctl" is used to program an OF entry with any
packets received with SRC_IP=23.0.0.1 as DROP. This flow is *NOT*
programmed in the kernel as it is an OF entry.

When a packet with SRC_IP=23.0.0.1 is received by kernel, it will get
punted to user_space because there is no match in kernel. vSwitchd would
subsequently updated the kernel with SRC_IP=23.0.0.1 with whatever action.
In the whole process OF flow does not seem to affect the datapath at all.

So the question is, how OF flow programmed thro' "ovs-ofctl" affects
datapath in the example considered above ?




On Fri, Apr 25, 2014 at 9:58 AM, Ben Pfaff <blp at nicira.com> wrote:

> None of that makes sense.
>
> On Fri, Apr 25, 2014 at 09:06:11AM -0700, Bhargav Bhikkaji wrote:
> > So, all OF-Flows are user-space switched and all Non-OF-flows kernel
> > switched (unless there is a flow miss).
> >
> > Do you expect a flow to be both OF & Non-OF ?. If so, how does it
> work-like
> > ?.
> >
> >
> > On Thu, Apr 24, 2014 at 3:50 PM, Ben Pfaff <blp at nicira.com> wrote:
> >
> > > No. No.
> > >
> > > On Thu, Apr 24, 2014 at 3:44 PM, Bhargav Bhikkaji
> > > <bhargav.ietf at gmail.com> wrote:
> > > > Does "ovs-ofctl flows" gets programmed in the kernel ? or is that
> > > > "ovs-dpctl dump-flows" dumps both of-flows & flows that got punted ?
> > > >
> > > >
> > > > On Thu, Apr 24, 2014 at 3:38 PM, Ben Pfaff <blp at nicira.com> wrote:
> > > >>
> > > >> On Thu, Apr 24, 2014 at 03:37:12PM -0700, Bhargav Bhikkaji wrote:
> > > >> > My actual question is, if there is flow miss in the datapath, the
> > > packet
> > > >> > is
> > > >> > punted to the user-space (vswitchd) which programs the missed
> flow on
> > > >> > datapath. Essentially, vswitchd handles the flow management for
> > > >> > datapath.
> > > >> > Is there a way to dump in vswitchd those flows that got punted and
> > > gets
> > > >> > programmed subsequently in datapath ?
> > > >>
> > > >> The flows that got punted and programmed are the flows dumped by
> > > >> "ovs-dpctl dump-flows".
> > > >
> > > >
> > >
> > >
> > >
> > > --
> > > "I don't normally do acked-by's.  I think it's my way of avoiding
> > > getting blamed when it all blows up."               Andrew Morton
> > >
>
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