The TCP/IP (Transmission Control Protocol/Internet Protocol) model is a framework that defines how data is sent and received over the internet. It is used in practice to operate modern networks, such as the internet, and allows devices (computers, phones, servers) to communicate efficiently. Unlike the OSI model, which is more theoretical, TCP/IP is a practical model, designed to meet the real-world needs of internet communication. It consists of four layers, each with a specific role.
The TCP/IP model is organized into four layers, which work together to send and receive data. Let's take the example of a video you're watching on YouTube. The first layer, called the Application layer, handles the applications you use directly, such as a web browser or a messaging app. In our example, YouTube prepares your video request for sending, using protocols like HTTP or HTTPS. The second layer, the Transport layer, ensures that the data arrives correctly and in the correct order. Here, TCP breaks the video into small packets and checks that nothing is missing, while UDP could be used for faster but less reliable transmissions.
Next, the third layer, the Internet layer, is responsible for finding the best path to send the data. The IP protocol assigns a unique address to your device and YouTube's server, then determines the path the packets should take, much like a mailing address for your data. Finally, the fourth layer, the Network Access layer, handles the physical transmission of data, whether via an Ethernet cable or Wi-Fi. In our example, it's your Wi-Fi or 4G connection that carries the video data to your screen.
The TCP/IP model is omnipresent in our daily lives, even if we don't think about it. Let's return to the example of the YouTube video. When you select a video, the Application layer (YouTube) sends a request to the server. The Transport layer, via TCP, ensures that the video packets arrive in the correct order. The Internet layer, with IP, finds the path between your device and the YouTube server. Finally, the Network Access layer uses your Wi-Fi or 4G connection to transport the data. In a few seconds, the video is ready to watch, thanks to the seamless coordination of the four layers of TCP/IP.
The OSI model, or Open Systems Interconnection, which we discussed earlier, is a theoretical framework divided into seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. The TCP/IP model, on the other hand, is more practical and simplified, with only four layers: Network Access, Internet, Transport, and Application. A major difference lies in the way the layers are organized. For example, the Session and Presentation layers of the OSI model, which handle connection management and data formatting, are integrated into the Application layer of TCP/IP. Similarly, the Physical and Data Link layers of OSI are combined into the Network Access layer of TCP/IP.
Another important distinction is the approach taken by the two models. The OSI model is a conceptual tool, often used to teach networking basics and explain how communication should ideally be structured. TCP/IP, on the other hand, is an operational model, designed for real-world use, particularly for operating the Internet. In other words, the OSI model offers a theoretical view, like a "perfect rule," while TCP/IP shows how things work on the Internet in practice. For example, the OSI model details steps like session management, but TCP/IP simplifies these aspects for more straightforward implementation.
The TCP/IP model is the foundation of the internet and modern networks. Without it, everyday actions like browsing websites, sending emails, or streaming videos would be impossible. Protocols like HTTP and HTTPS, which allow you to access websites, or SMTP, which sends your emails, rely on TCP/IP. Similarly, apps like WhatsApp or streaming services like Netflix and YouTube depend on this model to function. Although simpler than the OSI model, TCP/IP is powerful, connecting billions of devices around the world smoothly and efficiently.
The TCP/IP model is a practical four-layer framework (Application, Transport, Internet, Network Access) that enables the internet to function. Compared to the OSI model, which offers seven more theoretical layers, TCP/IP is simplified and directly applied in reality. These two models, although different, allow us to understand and organize communication between devices, making actions such as surfing the web, sharing files, and communicating remotely possible. Thanks to TCP/IP, the world is more connected than ever.
Want to learn more? Check out our other articles on computer networks, protocols, and network types!
