[ovs-discuss] Questions about IPFIX

Felix Konstantin Maurer felix.maurer at comsys.rwth-aachen.de
Tue Jun 6 12:18:32 UTC 2017


I accidentally only responded to you, so here again what I wrote.
Thanks for the quick response! If tested it now but so far I see no
difference. All IPFIX packets have the same flowStartDelta and flowEndDelta.

Furthermore, about the first lines in ipfix_cache_aggregate_entries?

line 1457
    to_start = &to_entry->flow_start_timestamp_usec;
    to_end = &to_entry->flow_end_timestamp_usec;
    from_start = &from_entry->flow_start_timestamp_usec;
    from_end = &from_entry->flow_end_timestamp_usec;

    if (*to_start > *from_start) {
        *to_start = *from_start;
    }
    if (*to_end < *from_end) {
        *to_end = *from_end;
    }

Is that not supposed to update the timestamps of the old entry, into
which the new stats are merged?

Regards
Felix

On 06/06/2017 01:16 AM, Greg Rose wrote:
> On 06/02/2017 03:06 PM, Ben Pfaff wrote:
>> On Fri, Jun 02, 2017 at 02:42:49PM -0700, Greg Rose wrote:
>> > 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.
>>
>> Seems reasonable.
>>
> I've posted a patch for this here:
> 
> https://patchwork.ozlabs.org/patch/771459/
> 
> Felix,
> 
> can you test it?  I'm getting set up to test ipfix but probably won't be
> able to test the patch until tomorrow.
> 
> Thanks,
> 
> - Greg

-- 
RWTH Aachen University
Communication and Distributed Systems
http://www.comsys.rwth-aachen.de

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