so I have just stared to learn OSI model and I can't understand why do we need IP on the third layer AND MAC addresses on the second layer.
From what I understand MAC addresses are used to move frames between nodes of a network (routers change source MAC address and destination MAC address as frame go through network)
1.Why do we need MAC addresses to do that? Can't we just use IP addresses of routers along the way? 2.Are MAC addresses just a redundancy? 3.Is it possible to somehow create a network model which would only use IP addresses? Just a single id number for each device in network