[mrtg] Re: MRTG methodology

[Dana Hudes]

mrtg uses snmp
I posted the relevant RFC#s to the list within the last few days.

as to the 2nd question, if you clear the counters then that will certainly drive the
curve down just as a rollover within the sample interval would.

btw 5 minutes is an awful lot of polling. consider whether you can live with
less fine-grain information. I run now at 15 minutes monitoring an E1, but if you have a T3 that would
not be a good idea.
----- Original Message ----- 
From: "Tyler J. Frederick" <tyler at sportsline.com>
To: "mrtg" <mrtg at list.ee.ethz.ch>
Sent: Thursday, September 27, 2001 12:41 PM
Subject: [mrtg] MRTG methodology


> 
> Hi guys,
> 
> I'm new to the list so bear with me if this is answered elsewhere or in
> previous posts.  (I've searched the archive and scoured the web page, so I
> don't think it is.)
> 
> I'm curious as to how MRTG actually works.  I know pretty much what's
> going on, but I'm about to use MRTG to graph some information on a
> Firewall-1 machine and want a better understanding.  This is assuming the
> default interval of 5 mins.
> 
> Let's look at a router for example.  It queries the ifInOctets and
> ifOutOctets OIDs, which I understand to be cumulative counters of the
> amount of bytes that have traversed that interface.
> 
> I think my question is this.  What happens if those counters were to be
> cleared? (by a 'clear counters' on a Cisco for example).  Would all my
> graphs have a spike down to zero on them?  How exactly does the averaging
> work?  I know I can put the 'guage' keyword in the options to signify that
> the data is a 'current status' measurement and not a cumulative one, but
> I'd like to better understand how MRTG does it's data calculation.
> 
> Thanks in advance!
> 
> tf.
> 
> 
> 
> -- 
> Tyler J. Frederick
> Systems Engineer/CCSE
> Sportsline.com, Inc.
> 
> 
> --
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