Physical Layer in OSI Model in Computer Networks

The Physical Layer in the OSI Model, which is a physical and electrical representation of the system, is the lowest layer. It has various network components such as power plugs, connectors, receivers, and different cable kinds. This layer transports data bits from one device (such as a computer) to another (s). The types of encoding (how the 0s and 1s in a signal are encoded) are defined by the Physical Layer. It is in charge of transmitting unstructured raw data streams across a physical channel.

Functionalities of Physical Layer in OSI Model:

This layer performs the following crucial and fundamental functions:

The Physical Layer maintains data rate( how many bits a sender can send per second).

It achieves bit synchronization.

It aids in the selection of a transmission medium (direction of data transfer).

This layer aids in the selection of Physical Topology (Mesh, Star, Bus, Ring) (Topology through which we can connect the devices with each other).

It aids in the selection of Physical Medium and Interface.

There are two sorts of configurations available: point to point and multi-point.

It acts as a link between devices (such as PCs or computers) and the transmission medium.

It has a bit-based protocol data unit.

This layer makes use of hubs, Ethernet, and other devices.

This layer belongs to the Hardware Layers category (since the hardware layer is responsible for all the physical connection establishment and processing too).

Modulation, which is the process of transforming data into radio waves by adding information to an electrical or optical nerve signal, is an important feature.

It also has a switching mechanism for forwarding data packets from one port (sender port) to the leading destination port.

Modes of Transmission Mediums:

  • Simplex mode : Only one of the two devices can transmit data in this mode; the other device can only receive data. Input from keyboards, monitors, TV broadcasting, radio broadcasting, and other sources, for example.
  • Half Duplex mode : In this mode, both devices can send and receive data, but only one at a time, rather than simultaneously. For example, a walkie-talkie, a railway track, and so on.
  • Full Duplex mode : Both devices can send and receive data simultaneously in this mode. For instance, a telephone system, chat programs, and so on.