I am learning about the OSI model and TCP/IP Protocol.
In my understanding, they classify cables to layer 1 (Physical Layer). But, when you connect two different devices you have to use cables no matter what levels you want to connect (type varies by standards but basically, it's required). (a host -> router, a router -> switch, etc).
So, When I connect A computer to my router directly. It only reaches layer 3, I still need a cable though, right? What is the definition of cable in this case? What sort of layer can I put the cable to?