One of my passions in technology is networking, another passion is open source and linux. So sometimes I come across networking software or just to play around with linux standard networking tools like iptables, tc or iproute2, or even play with open source implementations of routing protocols using Quagga/Bird/FRR/go-bgp.
I always found hard when testing this tools to get a proper setup on my laptop. Off course there are some tools that already help us in this regard like GNS3.