[ovs-discuss] Resending request for a new API between controller and switch

[Ben Pfaff]

The OVS datapath extracts the packet headers then looks for a match in
its flow table.  What part of that is the "flow index"?

On Tue, Jan 06, 2015 at 02:01:51PM -0800, Ashok Chippa wrote:
> Okay. How does the OVS datapath know this is a new flow? i.e. there is no
> matching flow entry? Doesn't it derive some sort of an index (into the flow
> table) from packet header fields? What am I missing? :)
> 
> If this is explained in details somewhere, I would appreciate the pointer.
> 
> Thanks,
> ashok
> 
> On Tue, Jan 6, 2015 at 1:43 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Tue, Jan 06, 2015 at 11:01:08AM -0800, Ashok Chippa wrote:
> > > Perhaps once you understand, it will make sense? :)
> > >
> > > Call it whatever flow_id or cookie or xyz? Let me call it "flow index"
> > for
> > > the sake of this discussion. The ovs datapath has some sort of a flow
> > index
> > > to look into the flow table when a packet arrives, right? Now, how does
> > the
> > > ovs datapath arrive at this flow index (upon a packet arrival)? It takes
> > > certain match parameters (from the packet header and perhaps some
> > > metadata)  and hashes them, right?
> >
> > I don't think you understand how the OVS datapath works.
> >