2025-09-14
In today's digital world, understanding how computers communicate over networks matters more than ever. Whether sending an email, browsing a website, or streaming video, data travels across networks through communication models. Two foundational models you need to know are the TCP/IP model and the OSI model. Although these may sound complex at first, breaking them down reveals their real purpose and usefulness. This article will help you grasp the basics of both models, compare their key differences, and explain when and why each one plays an important role.
Both models act as frameworks explaining how data travels between devices on a network. However, they differ in their structure, protocols, and practical uses. By the end of this guide, you will understand how these models work and why TCP/IP drives internet communication while OSI serves as an essential learning tool.
The International Standards Organization (ISO) created the OSI model, which stands for Open Systems Interconnection, in the 1980s to provide a clear framework for how different networking protocols communicate. The model divides network communication into seven distinct layers. Each layer performs a unique function, and data moves through these layers step-by-step.
From bottom to top, the seven OSI layers are: Physical, Data Link, Network, Transport, Session, Presentation, and Application. For example, the Physical layer manages the actual transmission of data through cables or wireless signals, while the Application layer handles software applications like web browsers and email clients.
Because the OSI model clearly separates each networking task, it serves as a great teaching tool. It helps students, engineers, and developers understand data handling at every stage. Although the OSI model offers detailed guidance, most networks do not implement it fully; instead, they use it as a standard reference when designing or troubleshooting networks.
Let’s explore the OSI model’s seven layers in beginner-friendly terms.
This layered design helps break complex network communication into manageable parts, making it easier to develop and troubleshoot network systems.
The TCP/IP model takes a more practical and simplified approach compared to OSI. The US Department of Defense designed it in the 1970s to support reliable, scalable communication across interconnected networks, which became the foundation of the internet.
This model organizes network communication into four layers: Application, Transport, Internet, and Network Access. Some OSI layers combine in TCP/IP—the OSI’s Application, Presentation, and Session layers merge into a single Application layer in TCP/IP.
Since TCP/IP focuses on real-world protocols, it uses standards like TCP for reliable communication and IP for routing and addressing. Its simplicity and practicality make TCP/IP the dominant model underpinning modern networks worldwide.
Here’s what each TCP/IP layer does:
Because of its straightforward design and standardized protocols, TCP/IP forms the backbone of all internet communication.
| Parameter | OSI Model | TCP/IP Model |
|---|---|---|
| Full Form | Open Systems Interconnection | Transmission Control Protocol / Internet Protocol |
| Number of Layers | 7 layers (Physical, Data Link, Network, Transport, Session, Presentation, Application) | 4 layers (Network Access, Internet, Transport, Application) |
| Purpose | Conceptual reference model for understanding and designing networks | Practical model used for real-world networking and the Internet |
| Layer Structure | Strict layer-by-layer architecture; each layer has a distinct function and communicates only with adjacent layers | Flexible architecture; layers can overlap and interact more freely |
| Protocol Dependency | Protocol-independent; does not specify exact protocols | Protocol-dependent; defines specific protocols like TCP, IP |
| Error Handling | Present in Data Link (frame errors) and Transport layers (end-to-end reliability) | Mainly handled by Transport layer protocol TCP; UDP provides no reliability |
| Development Body | Developed by ISO (International Organization for Standardization) | Developed by DARPA (US Department of Defense) |
| Implementation | Used mainly as a theoretical model and learning tool | Widely implemented and forms the backbone of the Internet |
| Layer Consolidation | Separate Session and Presentation layers | Session and Presentation functionalities included in Application layer |
| Usage and Adoption | Limited real-world adoption; primarily a teaching tool | High adoption and usage in practical networking |
TCP/IP gained dominance because its design suits real-world network conditions. It offers scalability, robustness, and flexibility needed to handle diverse and expanding networks that form the internet.
TCP/IP’s simpler four-layer structure ensures easier implementation and compatibility among various devices. Key protocols like IP, TCP, UDP, HTTP, and FTP directly support essential internet functions, enabling reliable global communication.
TCP/IP’s adaptability allows it to evolve with new technologies easily, unlike the more rigid OSI framework.
Why bother learning OSI when TCP/IP runs the internet? The answer lies in OSI's clear conceptual framework. It breaks down network communication into detailed, isolated layers, which helps troubleshooters and engineers pinpoint problems efficiently.
Moreover, understanding OSI deepens your appreciation for how different protocols and hardware fit together. Networking professionals and students pursuing certifications often use the OSI model to build solid foundational knowledge.
Both OSI and TCP/IP models offer valuable insights into network communication. TCP/IP provides the practical, real-world blueprint that powers internet communication today with simplicity and flexibility.
Meanwhile, OSI offers a comprehensive, structured way to learn, design, and troubleshoot networks by separating communication into seven clear layers.
Learning both models equips you with the knowledge to handle modern networking challenges effectively. Whether you aim to apply your skills practically or understand theory deeply, mastering these models will advance your networking expertise.
Absolutely! Extratech’s 12-week program is meticulously crafted to guide you through the exact knowledge and skills needed to succeed in globally recognized IT certification exams. Unlike generic courses, Extratech’s curriculum is directly mapped to the official exam objectives of certifications such as CompTIA A+, Network+, CCNA, Microsoft Azure Fundamentals (AZ-900), Azure Administrator (AZ-104), Microsoft 365 Fundamentals (MS-900), and ITIL v4 Foundation. This targeted approach means you’re not just absorbing theory; you’re training to confidently pass real-world exams. The course combines structured lessons, hands-on labs, and simulated test environments, ensuring you are exam-ready and equipped to apply your skills practically. Expert instructors simplify complex concepts and support you with mock exams, revision materials, and personalised mentoring, so you understand both the “what” and the “why” behind the content. These certifications carry international weight, boosting your credibility and opening doors to stable, well-paid IT roles in Australia and beyond.
Extratech goes beyond technical training by embedding comprehensive career development into the program. You’ll receive personalized coaching in crafting polished, AI-enhanced resumes and cover letters, optimizing your LinkedIn profile for maximum visibility, and devising strategic job search plans. The training also prepares you for technical and behavioural interviews and hones your professional communication skills. This holistic support ensures you’re not only qualified but also competitive and confident in the job market, positioning you for real success in the IT industry.
No prior IT knowledge or experience is required. This course is designed specifically for beginners, starting with foundational concepts and progressing step-by-step. The learning environment is supportive and structured to make even complex technical topics accessible. By the end of the program, you’ll have practical skills and the confidence to pursue IT roles immediately.
Extratech’s training equips you to sit for a range of respected certifications, including:
These certifications are widely recognized in the IT sector and serve as formal proof of your expertise to employers.
Extratech’s Cloud, Network and System Support Training is not just a course. It’s a comprehensive pathway to certification, employment, and long-term success in IT.
Extratech is an all-around Managed Service Provider (MSP), and purveyor of ICT Education, offering customized & personalized IT and digital performance, management, and education services. We provide the best Accounting & IT Training Courses and Certifications in Australia, Sydney, Canberra, Melbourne, Brisbane, Perth and Adelaide.