Thanks my freind,up to 70 devices.
Yes i want to install it on my PC.I`v tried to use CNA,but there is not support for Cisco 2960-L.
Is there other tool beside PRTG?
On PC with 70 device may be more i guess, if you have dedicated PC or Server want to use Opensource Linux based many available ( again depends how depth knowledge you have on Linux and Monitor tools) PRTG is easy to clicks so i suggested,
you can find good free tools below :