• OSI model was developed by the International Organization for Standardization (ISO) in 1984, and it is now considered as an architectural model for the inter-computer communications.
  • The open systems interconnection (OSI) model is a conceptual model created by the International Organization for Standardization which enables diverse communication systems to communicate using standard protocols.
  • OSI model divides the whole task into seven smaller and manageable tasks.
  • Each layer is assigned a particular task. Each layer is self-contained, so that task assigned to each layer can be performed independently.

7 Layers of the OSI Mode are as follows:-

1. Physical Layer:

The lowest layer of the OSI Model is concerned with electrically or optically transmitting raw unstructured data bits across the network from the physical layer of the sending device to the physical layer of the receiving device. It can include specifications such as voltages, pin layout, cabling, and radio frequencies. At the physical layer, there are resources such as network hubs, cabling, repeaters, network adapters or modems.

2. Data Link Layer:-

The data link layer takes packets from the network layer and breaks them into smaller pieces called frames. Like the network layer, the data link layer is also responsible for flow control and error control in intra-network communication. The data link layer also corrects errors that may have occurred at the physical layer.

Data link layer encompasses two sub-layers of its own. The first, media access control (MAC) which provides flow control and multiplexing for device transmissions over a network. The second, the logical link control (LLC) which provides flow and error control over the physical medium as well as identifies line protocols.

3. Network Layer:

Network layer is responsible for facilitating data transfer between two different networks. It determines the best path to move data from source to the destination based on the network conditions, the priority of service, and other factors. The network layer finds the destination by using logical addresses, such as IP (internet protocol). At this layer, routers are a crucial component used to quite literally route information where it needs to go between networks.

4. Transport Layer:

Transport Layer The transport layer manages the delivery and error checking of data packets. The main responsibility of the transport layer is to transfer the data completely. This layer can be termed as an end-to-end layer as it provides a point-to-point connection between source and destination to deliver the data reliably. One of the most common examples of the transport layer is Transmission Control Protocol (TCP).

5. Session Layer:

This layer controls the conversations between different computers. A session or connection between machines is set up, managed, and termined at layer 5. Session layer services also include authentication and reconnections. The Session layer is used to establish, maintain and synchronizes the interaction between communicating devices.

6. Presentation Layer:

Presentation layer focuses with the syntax and semantics of the information exchanged between the two systems. Because of this, it is sometimes also called the syntax layer. It acts as a data translator for a network. This layer is a part of the operating system that converts the data from one presentation format to another format.

7. Application Layer:

This layer provides the network services to the end-users. In this layer, both the end user and the application layer interact directly with the software application. It handles issues such as network transparency, resource allocation, etc. This layer is not an application, but it performs the application layer functions. The application layer identifies communication partners, resource availability, and synchronizes communication. Software applications like web browsers and email clients rely on the application layer to initiate communication