Networking - Network Models - OSI
The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a communication system or network into seven distinct layers. It was developed by the International Organization for Standardization (ISO) to promote interoperability and facilitate communication between different systems. Each layer of the OSI model performs specific tasks and communicates with adjacent layers using defined protocols.
The physical layer is the lowest layer of the OSI model and is responsible for the actual transmission of raw bits over a physical medium, such as cables or wireless signals. It deals with the electrical, mechanical, and physical aspects of data transmission.
Data Link Layer:
The data link layer provides error-free and reliable transmission of data frames between adjacent network nodes. It handles issues such as framing, flow control, error detection, and correction. Ethernet and Wi-Fi are examples of protocols that operate at this layer.
The network layer is responsible for the logical addressing and routing of data packets between different networks. It determines the optimal path for data transmission, handles network congestion, and provides logical addressing using IP (Internet Protocol). Routers operate at this layer.
The transport layer ensures reliable end-to-end data delivery between hosts. It segments data from the upper layers into smaller units and provides mechanisms for error recovery, flow control, and retransmission. The Transmission Control Protocol (TCP) operates at this layer.
The session layer establishes, manages, and terminates communication sessions between applications on different network devices. It handles session establishment, synchronization, and termination, allowing applications to exchange data in an orderly manner.
The presentation layer is responsible for the presentation and transformation of data in a format that is understandable by the receiving application. It handles tasks such as data encryption, compression, and data format conversion.
The application layer is the topmost layer of the OSI model and provides network services directly to the end-user applications. It includes protocols and services for tasks such as file transfer, email, web browsing, and remote access.
The OSI model provides a standardized framework for understanding and designing network architectures. It allows for modularity, enabling different layers to evolve independently. The model assists in troubleshooting, protocol design, and the development of interoperable network systems.