gns3 perhaps? I haven't had that setup for a while but I loved it. I had my whole small ISP in it at some point to work as a test/lab env for testing things out. It's a trick to get going but was kinda fun. I took a copy of that when I left and every now and then I fire it up and mess around with my old dsl/dialup ISP from back in the day.
Gameplay https://www.youtube.com/watch?v=Foa34qoRzjs
https://web.archive.org/web/20150317144142/https://cisco.edu...