hello all,
could you please tell me how much time it will take setting up (for the first time) :
MRTG, Cacti and Nagios on a network with ~25 routers and ~50 switches ?
i am a bit familiar with perl and shell scripting.
thanx in advance
Uh... Nagios does pretty much all of the features of Cacti... all of the above use RRD Tool...
Nagios > Cacti > MRTG > etc.
(read as blah greater than blah... etc)
With that said, we switched away from Nagios to just using Cacti... it all depends on WHAT your needs are. IMHO, if Nagios is interesting you probably want to look at ZenOSS as well. For graphs, we found Cacti to be better for monitoring things. Has a good community. Ideally, I'd like to write my own though...
thanx a lot, but may i ask :
- from what i have googled so far, the best thing to do is to have cacti polling the data, and then, through passive interfaces, feed these data in Nagios. is that correct ?
- why is the above a better solution than having nagios actively polling the devices and fill in the records in the rrd_tool ?
- and last, which is the simplest way of plotting the statistics in real-time (without requesting the plots) ?
thank you in advance 
hmmm... I don't see why Nagios can't do it.... again, our preference for Cacti has to do with they way it works and handles its interface and the maturity of the community it has.
Real time reporting usually means you're looking for something with a heavy handed poller.... which is NOT recommended. You can get very good "real time" information from controlled interval polling and that's what most these kinds of tools do.
The basically generate interval plots... not "live" data per se.
Since computer people like car analogies.... consider "miles per gallon" for a car. If I want instantaneous real time data for that... how is it possible? Well.. we could measure now and a microsecond from now... but with a small window, one sampling might show 400 mpg and the next sample might show me 1 mpg. The tools that use rrd-tool (and rrd-tool itself), understand the difficulties with such data which is why they work the way they do.
In other words it's not the right tool if you're looking for what is happening THAT VERY INSTANT.... IMHO of course.