MRTG does fine. Does switches too!
Follow the directions provided by the author very closely, except when one of the required packages may have changed its install procedure. I'm not a linux person and I got it, just gota follow and trust the instructions. I think that when I installed 7.2 RH workstation mode, it didn't have gcc (thats the C compiler I think), so I had to install it manually.
I don't know how much help I can be as I'm basically a novice that knows how to screw it up after I get it working.