Physical layer

The physical layer is the first layer in the OSI model which deals with the physical transmission medium. The data transferred via the physical layer is in the form of electrical signals. In a real life, we can treat the physical layer as the road where the vehicles are passing. Because the road is the one which is carrying the vehicles and linking the cities. Like that the physical layer is transmitting the data signal in the form of electrical signal and connecting nodes.

The major cables using in physical layer are:

1. Coaxial cable

2. Twisted pair cable

3. Optical fiber cable

Devices working in physical layer:

1. Internet gateway

2. Hub

3. Repeater


The major functions and services performed by the Physical Layer are:

1. Bit-by-bit delivery

2. Modulation

3. Encoding and Signaling:

4. Bit synchronization

5. Physical network Topology

In Physical Layer data is transmitting in the form of an electric pulse and the cables are responsible for the safe delivery of the signals. Physical Layer is also responsible for varying the waveform for the ease of data transfer. This process is known as modulation. The physical layer is also responsible for various types of encoding and decoding of signals. The physical layer also caring the transmission mode and physical layout of the network( topology)



The seven layer structure of the OSI Reference Model is listed below.

1. Physical layer
   
   
2. Data link layer
   
   
3. Network layer
   
   
4. Transport layer
   
   
5. Session layer
   
   
6. Presentation layer
   
   
7. Application layer