You’ve been there. You’re staring at a textbook diagram of a OSPF adjacency. The arrows look perfect. The dotted lines make sense. You close your eyes and think, “Yeah, I get it. Router A says hello, Router B replies, they swap link states...”
No, you don’t. Not for 90% of what you do. netsim network simulator
Then you get to the exam. Or worse—the production router. You’ve been there
But for the sake of this post, let’s treat netsim as the concept : Why you should ditch the physical lab (or the $10k hardware) I hear you: "But I need to test real code! ASICs matter!" Router B replies
