On Sat, 2009-01-31 at 11:24 +1300, Steve Shipway wrote: > Common problem (this really should be in an FAQ somewhere...?) > > If you are polling at the default 5-min interval, a 32-bit counter will wrap > at approximately 140Mbps. Since by default MRTG will use SNMPv1 you end up > using a 32bit counter unless you specify to use SNMPv2 and get the 64bit HC > counters. > > In your Target[] definitions, put a trailing :::::2 to specify to use SNMPv2, > eg: > > Target[foo]: 1:c...@device:::::2 > > This will use the 64bit counters, which can handle a rate of many many Gbps > before wrapping, event at 5min intervals! > > Another option is to use 1min intervals, but this only postpones the problem > until about 700Mbps. > > Always use SNMPv2 for any device supporting >100Mbps interfaces.
I don't think that's his problem, since he is using a 10-gig interface. How do you know that the graphs are "off"? Are you comparing them with the output of "show interface" on a Cisco Router? Show interface is an exponentially weighted estimate of the current bandwidth utilization. That variable is available for polling, but mrtg by default counts actual bytes, which gives you a linear approximation of the bandwidth used, rather than the exponentially weighted one. > > Steve > > ________________________________________ > From: [email protected] [[email protected]] On Behalf > Of Patrick Topping [[email protected]] > Sent: Saturday, 31 January 2009 6:33 a.m. > To: '[email protected]' > Subject: [mrtg] MRTG vs. Cricket > > I am hoping someone can help me out with this issue I am having..... I > am working on migrating from Cricket to MRTG. So far so good except > that the Cricket graphs are pretty spot on for a 5 minute interval while > the MRTG graphs are anywhere from 600 Mbps to 1 Gbps off at peak time. > For example, I have a 10-gig circuit that runs roughly at 7 Gbps a peak > time. Cricket graphs it damn near spot on. MRTG is off by almost a > full gig. > > _______________________________________________ > mrtg mailing list > [email protected] > https://lists.oetiker.ch/cgi-bin/listinfo/mrtg -- Daniel J McDonald, CCIE #2495, CISSP #78281, CNX Austin Energy http://www.austinenergy.com
signature.asc
Description: This is a digitally signed message part
_______________________________________________ mrtg mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/mrtg
