Collaborative computing/Physical layer

The Physical layer

the physical layer is the first layer in the OSI-model. It deals only with the transferring of bits through a communication channel. It is the layer which defines the electrical, physical and functional conditions that makes the physical connection between hosts possible.

Common Protocol design questions:

How many pins does the network connector have? Fx et RJ-45 Ethernet kabel

Billedeksempel på et RJ-45 kabel

How to represent a 0 and a 1 as an electric signal? There can exist a voltage difference in the specific wire

Is it possible to send data in both directions? Can you use the wire for sending in only one direction and how does data come back again?

All these questions should be taken into consideration when bits are sent from one computer to the other.