Installation on Ubuntu is straightforward; install Cacti on the Ubuntu management VM:

$ sudo apt-get install cacti

It will trigger a series of installation and setup steps, including the MySQL database, web server (Apache or lighthttpd), and various configuration tasks. Once installed, navigate to http://<ip>/cacti to get started. The last step is to log in with the default username and password (admin/admin); you will be prompted to change the password.

Once you are logged in, you can follow the documentation to add a device and associate it with a template. There is a Cisco router premade template that you can go with. Cacti has good documentation on http://docs.cacti.net/ for adding a device and creating your first graph, so we will quickly look at some screenshots that you can expect:

A sign indicating your SNMP is working would be that you to see able to see the device uptime:

You can add graphs to the device for interface traffic and other statistics:

After some time, you will start seeing traffic as shown here:

We are now ready to look at how to use Python scripts to extend Cacti's data-gathering functionality.