Re: [IPFIX] WG Last Call for draft-ietf-ipfix-information-model-rfc5101bis-03.txt

Hi folks

I have started looking through the changes and so far see the value in the various clarifications.  I'm a little concerned about the additional scope field being added to the Metering Process Statistics Options Template.  I see why that's been done, but what about existing implementations?


One minor point, in section 5:

   Certain time-related Information Elements may be expressed as an
   offset from this Export Time. For example, Data Records requiring a
   microsecond precision can export the flow start and end times with
   the flowStartMicroseconds and flowEndMicroseconds Information
   Elements [RFC5102bis], which encode the absolute time in microseconds
   in terms of the NTP epoch, 1 January 1900 at 00:00 UTC, in a 64-bit
   field. An alternate solution is to export the
   flowStartDeltaMicroseconds and flowEndDeltaMicroseconds Information
   Elements [RFC5102bis] in the Data Record, which respectively report
   the flow start and end time as negative offsets from the Export Time,
   as an unsigned 32-bit integer. This latter solution lowers the export
   bandwidth requirement, saving two bytes per timestamp, while
                                 ^^^^^^^^^^^^^^^^^^^^^^^
   increasing the load on the Exporter, as the Exporting Process must
   calculate the flowStartDeltaMicroseconds and flowEndDeltaMicroseconds
   of every single Data Record before exporting the IPFIX Message.


Isn't it saving 4 bytes per timestamp?


Regards, Andrew



On 23 Nov 2012, at 03:47, Nevil Brownlee <[email protected]> wrote:
> 
> Hi all:
> 
> Following up on Brian's email dated 20 November ...
> 
> The WG Last Call for this I-D starts now, and will run until Monday,
> 10 December.
> 
> Do please read the draft, and post your comments to the list.  It's
> important that we can show it has been well-considered/reviewed within
> the WG, so short comments like "yes, this does clearly describe the
> IPFIX Information Model as we want it to be" are important and useful!
> 
> Cheers, Nevil
> 
> -- 
> ---------------------------------------------------------------------
> Nevil Brownlee                    Computer Science Department | ITS
> Phone: +64 9 373 7599 x88941             The University of Auckland
> FAX: +64 9 373 7453   Private Bag 92019, Auckland 1142, New Zealand
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