[ovs-dev] Question about metadata matching

Junguk Cho jmanbal at gmail.com
Tue Aug 26 19:57:32 UTC 2014


Ok. I got it. Maybe I misunderstood the concept of metadata.
Metadata is passed between tables. It is not from packets.

One more question, if we used metadata, is metadata stored in "tun_in" in
"struct ovs_key_ipv4_tunnel"?
Which data structure keeps metadata information?

Thanks,
Junguk


2014-08-26 13:50 GMT-06:00 Ben Pfaff <blp at nicira.com>:

> Metadata is always 0 at the point that a packet enters the OpenFlow
> pipeline, so there's no need for the datapath to match on it--it would
> always be a match against 0.
>
> On Tue, Aug 26, 2014 at 01:44:56PM -0600, Junguk Cho wrote:
> > Oh, really?
> >
> > Basically, what I understood is datapath keeps some tables based on
> "struct
> > sw_flow_key" and  used  it for evaluating if incoming packet is matched
> or
> > not.
> >
> > Is it right or do I miss something?
> > If I miss something, can you forward me to metadata matching in datapath?
> >
> > Thanks,
> > Junguk
> >
> >
> > 2014-08-26 13:40 GMT-06:00 Ben Pfaff <blp at nicira.com>:
> >
> > > On Tue, Aug 26, 2014 at 01:36:04PM -0600, Junguk Cho wrote:
> > > > Hi, I have a simple question.
> > > > When we use metadata as flow-rule,
> > > > Does all traffic forward ofproto to match it because there is no
> match
> > > > field in "struct sw_flow" in datapath?
> > >
> > > No, metadata matching still allows for kernel forwarding.  There's no
> > > need to send every packet to userspace.
> > >
>



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