[rrd-users] Re: SNMP Total Traffic

Clifton Royston cliftonr at lava.net
Tue Jan 16 20:21:59 MET 2001

On Mon, Jan 15, 2001 at 07:30:34PM +0100, Alex van den Bogaerdt wrote:
> Aragon Gouveia wrote:
> > I'm currently using RRDtool to graph my network interfaces according to data
> > rate. I was wondering if it were possible to graph according to total
> > raffic over the interface in, say, a week? I need to know how many
> > megabytes of data is being transfered over the interfaces for billing
> > purposes. Is it possible with RRDtool? I can't figure out a way of doing it.
> > Any help is appreciated!
> The average number of bytes per second, multiplied with the number of
> seconds, gives you the number of bytes...
> So: display exactly one week and read the average.

  Not necessarily, depending on the prevalence of NANs stored in the
RRD, e.g. for intervals when the device was not being queried or when
it was unreachable.  An artifact of computing it this way is that you
can lose the accuracy of the data by transforming it to a rate and back

  The RRD will store NANs for the rate for this period; the NANs will
be ignored when constructing the average rate for the period.  Hence
the reconstructed data could be incorrect, because any such intervals
will be left out of the calculation (even though the byte counter value
before and after the interval was known), and hence the total number of
bytes calculated in this way could be more or less than the real value.
The adjustments RRD does in "averaging" the data might further compound
the problem.

  I have been wrestling with this issue myself and don't have a good
solution yet.

  -- Clifton

 Clifton Royston  --  LavaNet Systems Architect --  cliftonr at lava.net
      The named which can be named is not the Eternal named.

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