PHYSICAL LAYER

This is the first layer of the OSI Model. The physical layer is responsible for the physical cable or wireless connection between network nodes. It defines the connector, the electrical cable or wireless technology connecting the devices, and is responsible for the transmission of the raw data, which is simply a series of 0s and 1s while taking care of bit rate control.

The physical layer is the first and bottom-most layer of the OSI Model. It mainly provides the bit stream transmission. It also characterizes the media type, connector type and signal type to be used for communication. The raw data in the form of bits i.e. 0’s & 1’s are converted into signals and exchanged over this layer. Data encapsulation is also done at this layer.

Data Encapsulation: Encapsulation can be used to hide both data members and data functions or methods associated with an instantiated class or object.

To continue with the physical layer, the sender end and the receiving end should be in synchronization and the transmission rate in the form of bits per second is also decided at this layer. It provides a transmission interface between the devices and the transmission media and the type of topology to be used for networking along with the type of transmission mode required for transmission is also defined at this level.

Usually, star, bus or ring topologies are used for networking and the modes used are half-duplex, full-duplex or simplex. Examples of physical layer devices include;

• Hubs

• Repeaters

• Ethernet cable connectors.

These are the basic devices that are used at the physical layer to transmit data through a given physical medium which is suitable as per the network need.

In conclusion, physical layer is the transmission and reception of raw streams over a physical medium.