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I need to monitor the traffic rate in my LAN. I have installed nagios core 3.2 and I can monitor services like CPU load, disk usage, http server, etc. but now, How to monitor traffic?

I am using GNU/Linux Debian Squeeze in all the machines of my LAN.


Switch: Cisco 1900 series

I have tried this tutorial but it refers to files that does not exists in my system (eg. /usr/local/nagios/etc/objects/switch.cfg), I think is because of version.

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It would be helpful to know which plugins you have tried or looked at and what kind of router you are trying to monitor. – JamesCW Dec 13 '11 at 16:12
I wish I could answer your question directly, but after hours of frustration with Nagios, I installed Zenoss Core and never looked back. – SpacemanSpiff Dec 13 '11 at 22:53
I tried Zenoss core but I don't understand it. Some good tutorial for Zenoss core? – rendon Dec 14 '11 at 0:45

Nagios - Monitoring Switches and Routers

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Thanks but that is really useless, that manual is outdated. – rendon Dec 9 '11 at 20:02

For this kind of thing I use MRTG to record and graph the traffic and Nagios to alert based on what MRTG reads. Check out Nagios plugins such as check_rrd_bw.

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Are you sure you don't want a tool like MRTG? That's made for this sort of thing. The only wa i can think of would be using an SNMP GET from Nagios, but I've never used it for that... most of my remote stuff has been through NRPE.

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Have you used it? Do you think it will work? – rendon Dec 14 '11 at 0:47
I have used MRTG to monitor ingress/egress traffic on a cisco 3845 router with no issue. It produces nice graphs - you just have to make sure that you enable SNMP on the device you're trying to monitor (in case it isn't enabled by default). Check with the manufacturer for details. – Matthew Dec 14 '11 at 18:07
Ok, I'll try it! Thanks! – rendon Dec 16 '11 at 1:21

There are doezens and dozens of brand-specific SNMP plugins on and that will do this. On Nagios Exchange, for example, there are 37 plugins in the "Cisco" category.

You might also want to try the check_snmp_int plugin, here: I think it will work with switches, but you'd have to double-check to be sure.

Whether or not MRTG is a good answer to this question depends on what the asker means by "monitor"; MRTG will make nice graphs, and gather the data for you, but it does no alerting. Using check_mrtgtraf, you can have nagios "monitor" the MRTG data, this is a lot of work unless you already have MRTG set up.

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I mean monitor LAN bandwidth. Thanks for the info! – rendon Dec 29 '11 at 2:42

Once you've found a comfortable way to poll the data you're looking for, PNP4Nagios will give you a pretty good way to graph it automatically.

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