Introduction to network models
A networking model organizes and structures the protocols and standards that govern how devices communicate over a network.
(Protocols are sets of formal rules that define how network hardware and software interact and exchange data.)
In the early days of computing, networks were isolated and proprietary. Each manufacturer had its own standards, making communication between systems extremely difficult. As networks expanded and the Internet began to take shape, a universal framework was needed to standardize how devices communicate.
Two major models emerged:
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The OSI Model (1984, by ISO): A theoretical framework with 7 layers, designed to promote interoperability between systems. It is mostly used for learning, troubleshooting, and conceptual understanding.
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The TCP/IP Model (developed from the 1970s through ARPANET): A practical, simplified 4-layer model that forms the foundation of the Internet as we use it today.
Even though the OSI model is not directly implemented in real networks, it remains a powerful tool to describe and analyze network behavior.
🔍 Clarification: The OSI model is a theoretical framework created to help understand and teach how networks function. In contrast, TCP/IP is the practical protocol suite that governs real-world Internet communication.
Many TCP/IP protocols can be mapped to OSI layers, but the mapping is not one-to-one.
For example, the TCP/IP Application layer covers several OSI layers (Application, Presentation, and Session), while the Network Access layer covers both OSI’s Data Link and Physical layers.
As such, the OSI model helps structure our understanding, while TCP/IP powers the systems we use every day.
Why Network Models Matter in the Real World
| Purpose | Why It Matters |
|---|---|
| 🔍 Troubleshooting | Helps locate issues (cable? IP? port? service?) by layer. |
| 🛡️ Security | Understand attacks per layer (e.g., sniffing → L2, port scan → L4). |
| 🌐 Protocol Awareness | Know where protocols like DNS, TCP, IP, ARP operate. |
| 🧠 Clarity & Structure | OSI helps break down complex systems into clear layers (7 total). |
| ⚙️ Real-World Relevance | TCP/IP reflects how data truly flows on the Internet. |
| 🎓 Certs & Interviews | Common topic in exams & job interviews (e.g., “What happens when…?”). |