Nagios Support Forum

I'm doing an academic project at university with Nagios XI, but I need a scenario to test this service because I don't have a LAN segment or switches to plug and test. How can I do this? I am thinking of GNS3 but I have no idea how to do it. Can you help me ? Thanks for your time.

PS: I am using a VMWare virtual machine with centos 7 to use Nagios XI.