[ovs-discuss] DUMP-FLOWS: ofctl dump-flows vs dpctl dump-flows

Aaron Conole aconole at redhat.com
Thu May 18 16:38:44 UTC 2017


Levente Csikor <csikor at tmit.bme.hu> writes:

> Hi,
>
> a.f.a.i.k.:
>
> dpctl shows what's in the kernel space (fast path) and ofctl shows what's in the
> userspace (flow table - slow(er) path).
>
> The flow table can have priorities, therefore it can consist of overlapping rules as
> well resulting in lesser number of rules.
> On the other hand, the fast path builds a (megaflow-)cache according to the userspace
> flow-table(s) AND the incoming packets, in particular, incoming packets' headers
> (regardless of the action (forward/drop)).
>
> So, you not just see more rules/lines of output after calling dpctl command, they
> don't even be exactly the same.
>
> Please correct me, if I'm wrong.

That looks correct to me.

Additionally, Joe Stringer did an excellent talk about using ovs-dpctl -
https://www.youtube.com/watch?v=8ieoUQI7X88

This may help understand the difference between the two datapoints.

> BR,
> levi
>
> On 05/18/2017 03:17 PM, Avi Cohen (A) wrote:
>
>  I understand from manpages that dpctl shows only exact-match flows of packets that
>  traverse the datapath lately.
> So I expect to see less flows in the datapath than in openflow.  but I have  more flows in the datapath - why ?
>
>  -----Original Message-----
> From: Avi Cohen (A)
> Sent: Thursday, 18 May, 2017 4:37 PM
> To: 'ovs-discuss at openvswitch.org'
> Subject: DUMP-FLOWS: ofctl dump-flows vs dpctl dump-flows
>
> Hello,
> I'm seeing in my dpctl dump-flows   about 10,000  flows,  while in ofctl dump-
> flows I see only ~ 1400 flows
> - Is this make sense ?
> - How can I associate an ofcctl flow to a dpctl flow ?  (I can see ufid only in dpctl
> dump) Best Regards, avi
>
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