TCP/IP model

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The TCP/IP model is a widely used conceptual framework for computer networks and the basis for the Internet's architecture. It stands for Transmission Control Protocol/Internet Protocol and is named after the two core protocols it encompasses. The TCP/IP model was developed before the OSI model but has become the de facto standard for networking due to the widespread adoption of the Internet.

The TCP/IP model consists of four layers, as follows:

1. Application Layer:

   • Corresponds to the top three layers (Application, Presentation, and Session) of the OSI model.
   • It is the topmost layer responsible for providing network services directly to user applications.
   • This layer deals with high-level protocols that support specific network services, such as HTTP (HyperText Transfer Protocol) for web browsing, SMTP (Simple Mail Transfer Protocol) for email, and FTP (File Transfer Protocol) for file transfer.

2. Transport Layer:

   • Corresponds to the Transport layer of the OSI model.
   • This layer is responsible for end-to-end communication and reliable data transfer between applications running on different devices.
   • It defines two core protocols: TCP (Transmission Control Protocol) for reliable and connection-oriented communication and UDP (User Datagram Protocol) for unreliable and connectionless communication.
   • TCP ensures data delivery with error detection, retransmission, and flow control, while UDP is more lightweight and suitable for real-time applications like voice and video streaming.

3. Internet Layer:

   • Corresponds to the Network layer of the OSI model.
   • The Internet layer handles the routing and forwarding of data packets between different networks.
   • It is primarily governed by the Internet Protocol (IP) and deals with logical addressing, such as IP addresses, to uniquely identify devices on a network.
   • IP enables the best path selection for data transmission and defines how routers forward packets to their destination.

4. Link Layer:

   • Corresponds to the Data Link and Physical layers of the OSI model.
   • The link layer deals with the physical transmission of data over the network medium, such as Ethernet cables, Wi-Fi, or other physical connections.
   • It encompasses the Data Link layer's functions, which include error detection and correction, and the Physical layer's functions, dealing with the actual bits and signals transmitted over the physical medium.

Unlike the OSI model, the TCP/IP model is not divided into seven layers, and it combines the Presentation and Session layers' functions into the Application layer. Additionally, the TCP/IP model has less emphasis on the distinction between the Physical and Data Link layers, grouping them together as the Link layer.

The TCP/IP model's flexibility, simplicity, and compatibility with the Internet have made it the predominant networking model, guiding the design and implementation of networking protocols and applications worldwide.

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