Chapter 3. Physical Layer

Protocols of the physical layer are for the vast majority of users They are completely hidden protocols that describe signals on the connectors (commonly referred to as plugs) on the back part of the computer, to which a cable connecting the computer with the network is attached. Users tend to shift the responsibility to technical staff, whom they consider people "who take care of wires, by measuring something with a voltmeter." The situation today is completely different. A technician more or less administers software that controls all the mysterious boxes in locked rooms. This idea does not actually refer to the physical layer only, but encompasses the link layer as well. The users usually get involved only in the IP protocol (or network protocols), since in this protocol, they either see or do not see servers or neighbors. In contrast, the physical and link layers only provide communication with some kind of a box halfway down to the server...