[mrtg] Re: mrtg stats confirmation

[Paul C. Williamson]

The simple answer is it all depends on what you are querying.

If you are querying a device that returns actual values, like a Cisco router interface, it's easy - the number of bytes that have passed through the interface in the last 300 seconds.  If it's something like cpu on a Cisco device, depending on the OID used, that's easy too - 57 is the one minute average and 58 is the 5 minute average (both computed by the device independently of when you query the device for the value).  I will be the first to admit that MRTG can "miss" large peaks within the 5 minute window.  But, having said that, if there is not enough traffic to raise the 5 minute average enough to make it noticable, then it wasn't a big spike.  If it was large enough to move the 5 minute average up a few ticks, odds are it will be large enough to affect more than one 5 minute sample.

Just start calling your teammates Thomas.  They are doubting those stats now, but will become believers soon enough.  

If they doubt what MRTG says, they also have to doubt What's Up Gold, HP OV, IBM Director, CiscoWorks, NetView, VitalSuite, et al - they all query the same OIDs for values, and all measure on a 5 minute window.  MRTG is actually MORE accurate than some of these tools.  Not all do the "normalization" that MRTG calculates.  I don't include Sniffer in that group because the purpose of that tool is completely different from the others.

Paul

>>> "Mike Singleton" <msingle at davita.com> 11/20/01 18:05 PM >>>

Does anyone know of a simple way to explain the results of MRTG? My teammates doubt the veracity of the stats, and also don't understand the 5 minute averaging process... maybe a FAQ someone cold direct me to?


===
Mike Singleton CCNA, CNE, MCSE
Network Analyst
(253) 272-1916  x1259
(253) 405-1968 (cellular)
msingle at davita.com
DaVita Inc.


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