The OSI (Open Systems Interconnection) model is a conceptual framework that was developed by the International Organization for Standardization (ISO). It was designed to facilitate communication between various computer systems by dividing the process into seven distinct layers, each of which has a specific function.
In this article, we will take a deep dive into the seven layers of OSI and explore their functions.
Layer 1: Physical Layer
The physical layer is the lowest layer and is responsible for the transmission of raw data between devices. It defines the hardware requirements such as cables, connectors, and signaling methods. In other words, the physical layer is responsible for the physical connection between devices.
Layer 2: Data Link Layer
The data link layer is responsible for the reliable transfer of data between two nodes on the same network. It breaks the data into frames and adds addressing information to each frame. It also checks for errors in the transmission and retransmits any lost or damaged data.
Layer 3: Network Layer
The network layer is responsible for the delivery of data across multiple networks. It adds routing information to each packet and determines the best path for the data to reach its destination. This layer also handles congestion control and traffic management to ensure efficient communication between networks.
Layer 4: Transport Layer
The transport layer is responsible for reliable end-to-end delivery of data between two devices. It adds error checking, flow control, and congestion control to ensure data is transferred correctly. The transport layer also manages the connection between the sender and receiver.
Layer 5: Session Layer
The session layer is responsible for establishing, maintaining, and terminating communication sessions between applications. It manages the session by setting up, coordinating, and tearing down communication between two systems. This layer also maintains synchronization between the sending and receiving devices.
Layer 6: Presentation Layer
The presentation layer is responsible for converting data into a format that can be understood by the receiving device. It handles data encoding and decoding, data encryption, and data compression. The presentation layer also provides encryption services to ensure data security.
Layer 7: Application Layer
The application layer is the topmost layer of the OSI model and is responsible for providing access to network services for applications. It defines the protocols and services used by applications to communicate with each other. The application layer provides services like email, file transfer, and remote access.
In conclusion, the OSI model is a well-defined framework that maps the process of communication between different computer systems. Each layer has a specific function and is responsible for a particular task that contributes to the overall success of communication. Understanding the OSI model can be useful in troubleshooting network issues, designing new networks, and understanding modern networking technologies.