IP and routing is actually the interesting question. Somehow we need to get these IP packets to right place. And this opens up question how would it be done wit

IP and routing is actually the interesting question. Somehow we need to get these IP packets to right place. And this opens up question how would it be done with just IP packets? You would at least need some extra protocol over IP as IP itself really does not have idea where the next jump on the route is... Routing on Internet scale is messy question really. And then moving physical bits over any medium is also somewhat complicated always. So ethernet and MACs works relatively well for helping in both... Still, it is somewhat nice thought exercise to think how you would do without it.