[ovs-dev] [PATCH] ofproto-dpif-ipfix: add support for per-flow drop counters

Szczerbik, PrzemyslawX przemyslawx.szczerbik at intel.com
Thu Jun 22 08:19:39 UTC 2017


Hi Ben,

I'm having issues with configuring flows to see "sample" or "clone" actions during IPFIX upcall.
Most of the time I only see "userspace" and "output" actions, which surprises me quite a bit.
Even when I configure per-bridge IPFIX sampling there is no "sample" action.

I'd appreciate any suggestions how to configure flows to see those actions during IPFIX upcall.

Regards,
Przemek

> -----Original Message-----
> From: Szczerbik, PrzemyslawX
> Sent: Tuesday, June 20, 2017 8:46 AM
> To: Ben Pfaff <blp at ovn.org>
> Cc: dev at openvswitch.org
> Subject: RE: [ovs-dev] [PATCH] ofproto-dpif-ipfix: add support for per-flow drop
> counters
> 
> Hi Ben,
> 
> Thanks for your feedback. I can start working on implementing your suggestions.
> 
> Please keep in mind that IPFIX counters are based on probability, which means
> they won't necessarily reflect precise values.
> As you can see it's difficult to determine, with 100% accuracy, at sampling stage
> whether packet is going to be dropped at some point.
> I suppose there always is a possibility that next action might drop the packet and
> it we won't detect it.
> 
> I think that this patch (with addition of your requested changes) covers majority
> of cases which is good enough for IPFIX protocol.
> 
> Regards,
> Przemek
> 
> > -----Original Message-----
> > From: Ben Pfaff [mailto:blp at ovn.org]
> > Sent: Wednesday, June 14, 2017 10:23 PM
> > To: Szczerbik, PrzemyslawX <przemyslawx.szczerbik at intel.com>
> > Cc: dev at openvswitch.org
> > Subject: Re: [ovs-dev] [PATCH] ofproto-dpif-ipfix: add support for per-flow
> drop
> > counters
> >
> > On Tue, Jun 13, 2017 at 02:25:15PM +0100, Przemyslaw Szczerbik wrote:
> > > Patch based on RFC 5102, section 5.10. It implements per-flow drop counters:
> > > - droppedPacketDeltaCount
> > > - droppedPacketTotalCount
> > > - droppedOctetDeltaCount
> > > - droppedOctetTotalCount
> > >
> > > In order to determine if packet is going to be dropped, flow actions associated
> > > with packet are read. If there is no OVS_ACTION_ATTR_OUTPUT action,
> packet
> > will
> > > be dropped.
> > >
> > > Signed-off-by: Przemyslaw Szczerbik <przemyslawx.szczerbik at intel.com>
> >
> > Thanks for working on making the IPFIX support more complete.
> >
> > The code in this patch that detects whether an output action is present
> > is incomplete, for a couple of reasons.  First, it skips over "clone"
> > and "sample" actions that might contain output actions.  An output
> > action inside "clone" is truly an output.  An output action inside
> > "sample" is truly an output if the sampling probability is 100% (and the
> > datapath sometimes uses such a probability for technical reasons).
> > Whether an output action inside "sample" with a lower probability should
> > be considered an output is more questionable, but I don't think OVS ever
> > actually does that.
> >
> > The "userspace" and "recirc" actions raise bigger questions.  Either of
> > these can yield absolutely any kind of behavior, since userspace or the
> > recirculated flow table lookup's actions can do anything.  There's not
> > an easy way to decide whether a flow that executes one of these actions
> > truly drops anything.  Without taking a different approach, when one of
> > these actions is seen (and there isn't another clear output), the most
> > one can say is that the flow "might" drop the packet.
> >
> > I am not sure the best way forward.
> >
> > Thanks,
> >
> > Ben.
--------------------------------------------------------------
Intel Research and Development Ireland Limited
Registered in Ireland
Registered Office: Collinstown Industrial Park, Leixlip, County Kildare
Registered Number: 308263


This e-mail and any attachments may contain confidential material for the sole
use of the intended recipient(s). Any review or distribution by others is
strictly prohibited. If you are not the intended recipient, please contact the
sender and delete all copies.



More information about the dev mailing list