In my opinion one of the hardest things to get experience with in the IT industry is Network Monitoring software. Most of the big companies only offer trials if you are a company, so it’s hard to play around with monitoring software in a HomeLab set up. That is why i recommend PRTG by Paessler. It’s simple to use, supports everything from Linux devices to virtualization to Netflow capable devices and has a free version.
PRTG’s licensing is based on the number of sensors. A sensor is an individual item you want to monitor. As you can see in the picture I have a Ping Sensor set up on everything. Then depending on the device I have different sensors created. For example on the Cisco ASA 5505 I have Netflow, and bandwidth monitoring set up on certain ports. Further more PRTG tracks the history of the sensors and can report if a certain device is performing higher or lower then normal for a certain period of time.
With PRTG when you install the trial, the trial give you unlimited sensors to test out all the functionality. When the trial period is over, the free version is limited to 100 sensors. Which is a recent upgrade because originally the free version only included 30 sensors.
Go and check out PRTG its hands down one of the best network monitoring software products out there and it is the easiest product to set up in your HomeLab.