OSI Model and Its  layers

OSI stands for Open System Interconnection and acts as the model of reference that explains the communicative way between two computers. Just like humans can talk to each other to share information. Similarly, the computers can also talk to each other and pass on any information through an architectural model known as the OSI Model. This model is made up of 7 layers that enable it to function efficiently without any errors. 

The OSI model is basically divided into:

Upper Layer- this layer exists on the end user’s side and, most importantly, focuses on the application related problems. This is subdivided into the Application layer, Presentation Layer, Session Layer, and Transport layer.

Lower layer: this layer is mainly concerned with data transmission problems. It is subdivided into Network Layer, Data-Link Layer, and Physical Layer .

The seven layers are as follows:

  1. Application Layer
  2. Presentation Layer
  3. Session Layer
  4. Transport Layer
  5. Network Layer
  6. Data-Link Layer
  7. Physical Layer

Each layer has its own responsibility and plays its part individually to complete the whole process.

The Physical Layer and its functions

It is present at the foot of the OSI model and represents the physical and electrical parts of the system. It is made up of different network components like power plugs, connectors, receivers, cable types, etc. The core responsibility of this layer is to transmit as well as receive the undefined raw data that is present between a device and the physical transmission medium. The digital binary information (bits) is changed into electrical, radio or optical signals. It decides the way in which the data will be encoded, i.e., the way in which the 0’s and 1’s are encrypted in a signal.

Major Functions:

  1. The physical Layer maintains the flow of the information rate (the number of bits a sender sends in one second).
  2. It keeps the binary information in sync with one another.
  3. It decides and maintains the direction of data transfer.
  4. It also decides on which physical topology (i.e., mesh, star, bus, ring) to use in order to connect different devices with each other.
  5. It provides Physical Medium and Interface directions.
  1. It provides two sorts of configuration point to point configuration and multi-Point configuration.
  2. It provides a common point between the devices (like PCs or computers) and the transmission medium.
  3. The information provided through the physical layer is in the form of bits.
  4. Devices employed in this layer are Hubs, Ethernet, etc.
  5. This layer is categorised under the Hardware Layers (as the hardware layer is also provided with the establishment of physical connection and processing).
  6. It provides a very important facet known as Modulation, which is the method of changing the information into radio waves by adding the knowledge to an associate degree into an electrical or optical nerve signal.
  7. It conjointly provides a shift mechanism whereby information packets are often forward from one port (sender port) to the leading destination port.

Now let us look at the different network topologies that we mentioned above:

Network topologies- these are referred to as the geographical or topographical representation made between different devices linked to one another. They are of four types:

  • Mesh Topology: This is the node to node connection of devices and lacks a central connection point.
  • Star Topology: in this, there is a device located in the centre to which other devices are connected.
  • Bus Topology: Another name is line topology, in which all the devices are connected through a single cable.
  • Ring Topology: the devices are each connected to nodes, connecting no more than two nodes and forming a ring-like structure.

Conclusion:

All the layers of the OSI model work together with their own specific function and ensure the smooth functioning of the OSI Model. Among which is the physical layer that transports the data through a physical medium.