[mrtg] Re: Bandwidth Utilization questions

[Henry Steinhauer]

What I would suggest -

1 - Track the number of bytes moved over time, not the Utilization value.
2 - Remove the divide and multiply -
     As an aside, if you really needed to divide by a constant and then multiply
by 100 (which is also a constant), why not just  do the math once and divide the
constant by the other constant ?  That way you do not run into other issues with
scaling, or interger math.  (I suspect you are running into interger math issues
but the other suggestion will avoid that issue).

3 - Remember that the Full Duplex is 100 Mbit in Each Direction.  And ONLY 100
Mbit not 200 Mbit in  either direction that needs it.

4 - These changes would then require you to remove the guage option and the
nopercent option.
     The Percent would still be shown on the HTML pages so you could view that
if you like.
     You can then use the Bits option to show the Bytes in Bits if you like.
     --  In the current case, Bits has no meaning -  Bits of Percent Busy ?  The
Bits will take the value and multiply by 8.
          Most people know how big their files are in bytes and not in bits. but
this is just a sore spot in my analysis.
         I can talk with more people about the number of bytes being sent and
keep them listening if I show them the number of bytes per second.
         If I have to transalte for them from Bytes to bits, then I lose them.
They get that eye glaze look.

5 - I have found that over time, people tend to add more . . .  to the line
Maybe next year it will a Gigbit interface.  By tracking Bytes or Bits, then the
graph will continue to make sense.  If tracking Utilization, then Utilization of
What ?  What is the base ?  100 Mbit, 100 Gigbit,

6 - Making those few changes should give you some graphs of your traffic.


Henry Steinhauer





From: "Lehouillier, Neil" <Lehouillier at Northrock.ab.ca> on 08/23/2000 03:20 PM

To:   "'mrtg at list.ee.ethz.ch'" <mrtg at list.ee.ethz.ch>
cc:
Client:
Subject:  [mrtg] Bandwidth Utilization questions




I just have a couple of questions here:

1.  I am trying to monitor the bandwidth utilization of a 100 Mbit
Full Duplex line.  I have compared info from a sniffer on the line
and the info I gather from MRTG and found that the MRTG data is out
of wack.  Could someone please point out the mistake I'm making here.

Target[10.4.251.13.19]: 19:public at 10.4.251.13 / 100000000 * 100
MaxBytes[10.4.251.13.19]: 100
Title[10.4.251.13.19]: THEROCK - Module-1 Port-19
Options[10.4.251.13.19]: growright, gauge, nopercent, bits
PageTop[10.4.251.13.19]: <H1>Therock Network Utilization </H1>
Ylegend[10.4.251.13.19]: Network Utilization
ShortLegend[10.4.251.13.19]: Utilization
WithPeak[10.4.251.13.19]: wmy
Unscaled[10.4.251.13.19]: dwmy
LegendI[10.4.251.13.19]: Utilization
LegendO[10.4.251.13.19]:

Should I be dividing by 200000000 instead of 100000000 because its
full duplex?  Also should I be using 100 in the MaxBytes or should I
be using 25000000?

2.  Is the MaxBytes variable compared against the bytes that get
returned from the query or is it compared against the Target variable
that you specified?

Any help would be greatly appreciated.



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