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Polling an F5 Load balancer using MRTG and SNMP

After getting MRTG setup and running in my MRTG Virtual Appliance as I call it, I started setting up all my networking devices for monitoring.  One of the devices I really wanted to poll some more advanced data from is our Load Balancer.  What I really wanted to be able to see was the number of concurrent connections to the LB and each of the Virtual Servers if possible.  This proved to be much more complicated than I had anticipated.

My first problem is that my SNMP software in Ubuntu was not configured correctly.  By default the SNMPd was looking for /usr/share/snmp/mib to load the mib files.  In the version of Ubuntu that I had the path was /usr/share/snmp/mib2c-data so I had to update the snmp.conf file.  Once I did that then SNMP was able to correctly load all the add-on MIBs so that I could have the OID definitions load correctly.

My second problem was the the MIB file that I had gotten from the web was incorrect, or more to the point it was outdated.  The search that I did for F5 MIBs returned many hits, but the one that I went to for most of the information I started with was a nice post at  Unfortunately, I didnt realize that this was really out of date.  As a result the LOAD-BAL-SYSTEM-MIB.txt is invalid with the software version that my F5 is running and fails the OID lookups.

My F5 is hosted so I dont have direct access to the device.  I was able to get the hosting company to grab the MIB files from the filesystem of the F5, and then I put them into my /usr/share/snmp/mib2c-data directory.  After that my MRTG graphs for Virtual Server connections started working. One mistake that I made in this process was only putting some of the MIB files on my machine.  Do yourself a favor and just get ALL the MIBs and load them to your SNMP MIBs folder.

I found a nifty script here called that was able to do an snmpwalk and get all the information about my Virtual Servers that I needed to get current connections and bandwidth on a per VS basis.  From there MRTG was up and running with some pretty good stats about concurrent connection rate and bandwidth utilization across all my domains.

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MRTG Virtual Appliance

Over the last couple of weeks I have been working to build an MRTG server in our VM environment.  I wanted it to be very lightweight for CPU, RAM and Disk storage.

I've used MRTG quite a bit before and it can sometimes be tricky getting everything worked out just right so that it runs without babysitting.  I finally got a pretty good install going and thought I would share it up here for anyone who might find it useful.

This is an MRTG Virtual Appliance that is running on Ubuntu Server for Virtualization.  The install is very compact with just a 2gb virtual disk, 1 cpu and 512MB of RAM.  You can download the  MRTG_Appliance here.  Total file size is ~430MB.

MRTG is setup and configured as well as lighttpd as the webserver.  The server is configured for DHCP and SSH is enabled for console management.  There is no GUI but there is a configuration page linked from the default webpage.

This is a first run at creating an Appliance/OVA file for me, so I'm sure I have missed some steps.  I will update this page as well as the download file as any issues are identified.

Let me know how it goes so we can make it better!

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