[ovs-discuss] Questions about IPFIX

[Greg Rose]

On 06/02/2017 09:08 AM, Ben Pfaff wrote:
> ipfix_cache_entry_init() initializes the start and end to be the same:
>
>          xgettimeofday(&now);
>          entry->flow_end_timestamp_usec = now.tv_usec + 1000000LL * now.tv_sec;
>          entry->flow_start_timestamp_usec = entry->flow_end_timestamp_usec;
>
> and then I don't see anything that ever updates the "end" time.  I guess
> that's the issue.

 From looking at the code it appears to me that the ipfix_cache_update() function isn't doing
anything to update the time stamps.  It updates the stats but the stats function doesn't update
time stamps.  From what I can tell though that seems the place where it should be updated.  I can
try whipping up a bug fix patch for this if ipfix_cache_update() is the right place to do the time
stamp update.

- Greg



>
> On Fri, Jun 02, 2017 at 01:57:01PM +0200, Felix Konstantin Maurer wrote:
> > I just took a look at the code, and I think it should work, as the the
> > timestamps are properly updated in ipfix_cache_aggregate_entries.
> > However, I don't know the code base well or C for that matter.
> > Can you point me to where the time values are not properly set?
> >
> > Regards
> > Felix
> >
> > On 05/31/2017 05:27 PM, Ben Pfaff wrote:
> >> On Wed, May 31, 2017 at 03:05:45PM +0200, Felix Konstantin Maurer wrote:
> >>> I'm currently trying to export flow statistics from an Openvswitch
> >>> bridge with IPFIX. It works, however in almost all packets, the
> >>> flowStartDeltaMicroseconds and the flowEndDeltaMicroseconds have the
> >>> same value. Is that to be expected? Do I misunderstand something?
> >>>
> >>> I expected them to be different and to allow me to calculate over which
> >>> time period the octetDeltaCount number of bytes of the flow had been sent.
> >>
> >> The IPFIX code hard-codes the start and end times to the same value.
> >> It's too bad--it would be nice to have this be more accurate.  I don't
> >> know how difficult that would be.
> >>
> >
> > --
> > RWTH Aachen University
> > Communication and Distributed Systems
> > http://www.comsys.rwth-aachen.de
> >
>
>
> _______________________________________________
> discuss mailing list
> discuss at openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>