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Re: [ipfix-eval] Some comments on the evaluation team draft

Simon Leinen <simon@limmat.switch.ch> Thu, 14 November 2002 22:54 UTC

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To: Benoit Claise <bclaise@cisco.com>
Cc: ipfix-eval@net.doit.wisc.edu
Subject: Re: [ipfix-eval] Some comments on the evaluation team draft
References: <3DD3C6C3.30408@cisco.com>
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From: Simon Leinen <simon@limmat.switch.ch>
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Date: Thu, 14 Nov 2002 23:47:53 +0100
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On Thu, 14 Nov 2002 16:52:35 +0100, Benoit Claise <bclaise@cisco.com> said:
> 4.5 Time Synchronization  (5.5) LFAP: T     CRANE: T     IPDR: T
> NetFlow: P     Diameter: T

> In my draft
> http://www.ietf.org/internet-drafts/draft-claise-ipfix-eval-netflow-03.txt,
> I wrote

>     3.4.5 Time Synchronization (5.5)

>     _ Total Compliance. _
>     The export packet header contains the UTC time of the export packet
>     generation. This header also contains the router sysUpTime at the
>     time of the export packet generation. The UTC time the router booted
>     can therefore be deduced. The flow records contain the flow start
>     and flow end sysUpTime, so that the NetFlow collector can deduce the
>     flow start and flow end UTC time.

Yes, but the problem is (Mark Fullmer pointed this out) that the UTC
time field in the header only has 1-second resolution, so a collector
cannot convert flow timestamps to UTC times with the required
precision (centiseconds or better).

It could be fixed by making the UTC time field in the header more
precise.  I think earlier versions of NetFlow had this.
-- 
Simon.

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