I like the analogy, but explaining TCP and UDP is just a small subset of what I would consider 'networking'. Now explain how the horses and messengers find thei

I like the analogy, but explaining TCP and UDP is just a small subset of what I would consider 'networking'. Now explain how the horses and messengers find their way across the realm. Which roads are used and why? What happens when a road is closed and how can the closure of one road be propagated to the other roads.