[mrtg] Re: Aggregate Graphing

[Albinati, Luis Martin]

I had a similar problem measuring high speed interfaces like for example a
STM1s or Gigabit ports, the behaviour was exactly the same that you mention,
after doing some research i figured that the problem was SNMP itself since
SNMP V1 has 32 bit counters and when the speed of the interface you are
measuring exceeds some value over 100+something  (don't remember exactly)
the counters get back to zero before the 5 minute period in which MRTG makes
the poll, then in the first poll you get a value of 888888 and in the next
you get something lower like 444444, that's what makes MRTG do those ugly
graphs, the solution is to do the polls with SNMP V2 which has 64 bit
counters and so the values do not reset to 0 before the 5 minute period.
Hope it helps.

Best regards,

Luis Martin Albinati
N.O.C.
Prima S.A. - Argentina
Ciudad Internet / Datamarkets
Tel. #: (54)11-4379-4614
E-Mail: Albo at Prima.Com.Ar


-----Original Message-----
From: Brian E. Seppanen [mailto:seppy at chartermi.net]
Sent: Friday, December 14, 2001 9:38 AM
To: mrtg at list.ee.ethz.ch
Subject: [mrtg] Aggregate Graphing



Hi:

I'm trying to create a graph of aggregate bandwidth that is comprised of 5 
DS3's.   During peak times, when the totals are going above 100MB, the 
totals on the graphs inch up and then bottom out to about 50MB (As if some 
of the interfaces are no longer reporting SNMP values).   They are still 
showing traffic, but it drops to about 50MB, periodically it will spike 
back up to 100MB, and then the next poll will drop it back to 50MB.   
Some of the spikes are over the 100MB threshold so I wouldn't think that
this 
would be due to a max bytes setting.   This continues until eventually it 
reaches the 100MB thresh hold and then the graph stabilizes again.   Each 
of the individual graphs indicates that they are just fine, on the routers 
themselves.   I have tried tweaking the number of retries, backoffs and 
timeouts, although I'm back to default values in most cases.

An example of what my config looks like, with IP's and community's changed 
to protect the innocent.  

Target[total]: 1:community at 192.168.1.1::2:5:1: +
2:community at 192.168.1.2::2:5:1: + 3:community at 192.168.1.3::2:5:1: +
4:community at 192.168.1.4::2:5:1: + 5:community at 192.168.1.5::2:5:1:
MaxBytes[total]: 33157500 

...
.etc.

Thanks,

Brian Seppanen
seppy at chartermi.net
906-228-4226 ext 23


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