Outside, have the students get in a circle and hold hand to a person who is not next to them. This should make the students, all holding hands, in a kind of tangled knot. It looks like they're all interconnected, and that this would be a good way to have everything connected in the Internet. Now have the students untangle themselves without letting go. They will (eventually!) be in a circle, and this doesn't seem as efficient a way to connect everyone. Some connections are very long, and the ones that aren't can be made long if just one person in the chain breaks. Explain that hubs or routers work to be a source of lots of connections. Have one or two students each get several ropes. These students are routers. Make sure the routers are connected to each other (holding hands). In the other hand, have each router hold the ropes at the ends, and the rest of the students holds on to the other ends. Now, if a computer (not a router) stops their connection, it doesn't really affect anyone else's connections. This is a better model, or representation, of how the Internet works, and it works better than the human knot of before.