OSI Model

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The OSI (Open Systems Interconnection) model is a conceptual framework or guidelines used to understand and describe different networking protocols interacting within a computer network, developed by the International Organization for Standardization (ISO) in 1970s to create a standardized or structured way of discussing and understanding the complexities of network communication.

The OSI model divides network communication into seven distinct layers, each one is responsible for specific tasks, organized in a hierarchical manner, with each layer building upon the services provided by the layer below it, ensures that data moves from its point of origin to its destination efficiently and accurately.

The block diagram of seven layers are as follows:



Physical Layer (Layer 1): Physical layer lies at the base of the OSI model, focusing on the transmission of raw data bits through physical mediums such as cables, fibers, or wireless connections. It defines attributes like voltage levels, data rates, and physical connectors.

Data Link Layer (Layer 2): The Data Link Layer lies above the physical layer, establishes a reliable link between nodes within the same network, deals with framing, error detection, and flow control, ensuring data integrity over a local connection.

Network Layer (Layer 3): The network layer handles the transmission of data packets across different networks, using logical addressing and routing to determine the optimal path for data to reach its destination. IP (Internet Protocol) operates within this layer, facilitates communication between distinct networks.

Transport Layer (Layer 4): Transport Layer is above the network layer, manages end-to-end communication, ensuring data delivery, error correction, and flow control. Protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) operate at this level, providing reliable or connectionless data transfer, respectively.

Session Layer (Layer 5): The session layer establishes, maintains, and terminates communication sessions between applications. It enables synchronization, checkpointing, and recovery services, ensuring smooth interaction between devices.

Presentation Layer (Layer 6): Responsible for data representation and translation, the presentation layer ensures that data exchanged between systems is in a universally understandable format. It handles tasks such as encryption, compression, and formatting.

Application Layer (Layer 7): At the topmost layer, the application layer interacts directly with the end-user. It houses network applications and provides interfaces for user-related services like email, web browsing, and file transfer.

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