As computing technology evolved and the concept of linking multiple computers together into a “network” that could share data came into being, it was clear that a model was needed to define and enable those connections. Enter the OSI model in computer network idea.
This model allows various devices and software to “communicate” with one another by creating a set of universal rules and functions. Let’s dig into what the model entails.
History of the OSI Model
In the late 1970s, the continued development of computerized technology saw many companies start to introduce their own systems. These systems stood alone from others. For example, a computer at Retailer A has no way to communicate with a computer at Retailer B, with neither computer being able to communicate with the various vendors and other organizations within the retail supply chain.
Clearly, some way of connecting these standalone systems was needed, leading to researchers from France, the U.S., and the U.K. splitting into two groups – The International Organization for Standardization and the International Telegraph and Telephone Consultive Committee.
In 1983, these two groups merged their work to create “The Basic Reference Model for Open Systems Interconnection (OSI).” This model established industry standards for communication between networked devices, though the path to OSI’s implementation wasn’t as clear as it could have been. The 1980s and 1990s saw the introduction of another model – The TCP IP model – which competed against the OSI model for supremacy. TCP/IP gained so much traction that it became the cornerstone model for the then-budding internet, leading to the OSI model in computer network applications falling out of favor in many sectors. Despite this, the OSI model is still a valuable reference point for students who want to learn more about networking and still have some practical uses in industry.
The OSI Reference Model
The OSI model works by splitting the concept of computers communicating with one another into seven computer network layers (defined below), each offering standardized rules for its specific function. During the rise of the OSI model, these layers worked in concert, allowing systems to communicate as long as they followed the rules.
Though the OSI model in computer network applications has fallen out of favor on a practical level, it still offers several benefits:
- The OSI model is perfect for teaching network architecture because it defines how computers communicate.
- OSI is a layered model, with separation between each layer, so one layer doesn’t affect the operation of any other.
- The OSI model offers flexibility because of the distinctions it makes between layers, with users being able to replace protocols in any layer without worrying about how they’ll impact the other layers.
The 7 Layers of the OSI Model
The OSI reference model in computer network teaching is a lot like an onion. It has several layers, each standing alone but each needing to be peeled back to get a result. But where peeling back the layers of an onion gets you a tasty ingredient or treat, peeling them back in the OSI model delivers a better understanding of networking and the protocols that lie behind it.
Each of these seven layers serves a different function.
Layer 1: Physical Layer
Sitting at the lowest level of the OSI model, the physical layer is all about the hows and wherefores of transmitting electrical signals from one device to another. Think of it as the protocols needed for the pins, cables, voltages, and every other component of a physical device if said device wants to communicate with another that uses the OSI model.
Layer 2: Data Link Layer
With the physical layer in place, the challenge shifts to transmitting data between devices. The data layer defines how node-to-node transfer occurs, allowing for the packaging of data into “frames” and the correction of errors that may happen in the physical layer.
The data layer has two “sub-layers” of its own:
- MAC – Media Access Controls that offer multiplexing and flow control to govern a device’s transmissions over an OSI network.
- LLC – Logical Link Controls that offer error control over the physical media (i.e., the devices) used to transmit data across a connection.
Layer 3: Network Layer
The network layer is like an intermediary between devices, as it accepts “frames” from the data layer and sends them on their way to their intended destination. Think of this layer as the postal service of the OSI model in computer network applications.
Layer 4: Transport Layer
If the network layer is a delivery person, the transport layer is the van that the delivery person uses to carry their parcels (i.e., data packets) between addresses. This layer regulates the sequencing, sizing, and transferring of data between hosts and systems. TCP (Transmission Control Protocol) is a good example of a transport layer in practical applications.
Layer 5: Session Layer
When one device wants to communicate with another, it sets up a “session” in which the communication takes place, similar to how your boss may schedule a meeting with you when they want to talk. The session layer regulates how the connections between machines are set up and managed, in addition to providing authorization controls to ensure no unwanted devices can interrupt or “listen in” on the session.
Layer 6: Presentation Layer
Presentation matters when sending data from one system to another. The presentation layer “pretties up” data by formatting and translating it into a syntax that the recipient’s application accepts. Encryption and decryption is a perfect example, as a data packet can be encrypted to be unreadable to anybody who intercepts it, only to be decrypted via the presentation layer so the intended recipient can see what the data packet contains.
Layer 7: Application Layer
The application layer is a front end through which the end user can interact with everything that’s going on behind the scenes in the network. It’s usually a piece of software that puts a user-friendly face on a network. For instance, the Google Chrome web browser is an application layer for the entire network of connections that make up the internet.
Interactions Between OSI Layers
Though each of the OSI layers in computer networks is independent (lending to the flexibility mentioned earlier), they must also interact with one another to make the network functional.
We see this most obviously in the data encapsulation and de-encapsulation that occurs in the model. Encapsulation is the process of adding information to a data packet as it travels, with de-encapsulation being the method used to remove that data added data so the end user can read what was originally sent. The previously mentioned encryption and decryption of data is a good example.
That process of encapsulation and de-encapsulation defines how the OSI model works. Each layer adds its own little “flavor” to the transmitted data packet, with each subsequent layer either adding something new or de-encapsulating something previously added so it can read the data. Each of these additions and subtractions is governed by the protocols set within each layer. A perfect network can only exist if these protocols properly govern data transmission, allowing for communication between each layer.
Real-World Applications of the OSI Model
There’s a reason why the OSI model in computer network study is often called a “reference” model – though important, it was quickly replaced with other models. As a result, you’ll rarely see the OSI model used as a way to connect devices, with TCP/IP being far more popular. Still, there are several practical applications for the OSI model.
Network Troubleshooting and Diagnostics
Given that some modern computer networks are unfathomably complex, picking out a single error that messes up the whole communication process can feel like navigating a minefield. Every wrong step causes something else to blow up, leading to more problems than you solve. The OSI model’s layered approach offers a way to break down the different aspects of a network to make it easier to identify problems.
Network Design and Implementation
Though the OSI model has few practical purposes, as a theoretical model it’s often seen as the basis for all networking concepts that came after. That makes it an ideal teaching tool for showcasing how networks are designed and implemented. Some even refer to the model when creating networks using other models, with the layered approach helping understand complex networks.
Enhancing Network Security
The concept of encapsulation and de-encapsulation comes to the fore again here (remember – encryption), as this concept shows us that it’s dangerous to allow a data packet to move through a network with no interactions. The OSI model shows how altering that packet as it goes on its journey makes it easier to protect data from unwanted eyes.
Limitations and Criticisms of the OSI Model
Despite its many uses as a teaching tool, the OSI model in computer network has limitations that are the reasons why it sees few practical applications:
- Complexity – As valuable as the layered approach may be to teaching networks, it’s often too complex to execute in practice.
- Overlap – The very flexibility that makes OSI great for people who want more control over their networks can come back to bite the model. The failure to implement proper controls and protocols can lead to overlap, as can the layered approach itself. Each of the computer network layers needs the others to work.
- The Existence of Alternatives – The OSI model walked so other models could run, establishing many fundamental networking concepts that other models executed better in practical terms. Again, the massive network known as the internet is a great example, as it uses the TCP/IP model to reduce complexity and more effectively transmit data.
Use the OSI Reference Model in Computer Network Applications
Though it has little practical application in today’s world, the OSI model in computer network terms is a theoretical model that played a crucial role in establishing many of the “rules” of networking still used today. Its importance is still recognized by the fact that many computing courses use the OSI model to teach the fundamentals of networks.
Think of learning about the OSI model as being similar to laying the foundations for a house. You’ll get to grips with the basic concepts of how networks work, allowing you to build up your knowledge by incorporating both current networking technology and future advancements to become a networking specialist.
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Computer Science is fast becoming one of the most valuable fields of study, with high levels of demand and high-salaried career opportunities for successful graduates. If you’re looking for a flexible and rewarding way to hone your computing skills as part of a supportive global community, the BSc in Computer Science at the Open Institute of Technology (OPIT) could be the perfect next step.
Introducing the OPIT BSc in Computer Science
The OPIT BSc in Computer Science is a bachelor’s degree program that provides students with a comprehensive level of both theoretical and practical knowledge of all core areas of computer science. That includes the likes of programming, databases, cloud computing, software development, and artificial intelligence.
Like other programs at OPIT, the Computer Science BSc is delivered exclusively online, with a mixture of recorded and live content for students to engage with. Participants will enjoy the instruction of world-leading lecturers and professors from various fields, including software engineers at major tech brands and esteemed researchers, and will have many paths open to them upon graduation.
Graduates may, for example, seek to push on with their educational journeys, progressing on to a specialized master’s degree at OPIT, like the MSc in Digital Business and Innovation or the MSc in Responsible Artificial Intelligence. Or they could enter the working world in roles like software engineer, data scientist, web developer, app developer, or cybersecurity consultant.
The bullets below outline the key characteristics of this particular course:
- Duration: Three years in total, spread across six terms.
- Content: Core courses for the first four terms, a student-selected specialization for the fifth term, and a capstone project in the final term.
- Focus: Developing detailed theoretical knowledge and practical skills across all core areas of modern computer science.
- Format: Entirely online, with a mixture of live lessons and asynchronous content you can access 24/7 to learn at your own pace.
- Assessment: Progressive assessments over the course of the program, along with a capstone project and dissertation, but no final exams.
What You’ll Learn
Students enrolled in the BSc in Computer Science course at OPIT will enjoy comprehensive instruction in the increasingly diverse sectors that fall under the umbrella of computer science today. That includes a close look at emerging technologies, like AI and machine learning, as well as introductions to the fundamental skills involved in designing and developing pieces of software.
The first four terms are the same for all students. These will include introductions to software engineering, computer security, and cloud computing infrastructure, as well as courses focusing on the core skills that computer scientists invariably need in their careers, like project management, quality assurance, and technical English.
For the fifth term, students will have a choice. They can select five electives from a pool of 27, or select one field to specialize in from a group of five. You may choose to specialize in all things cybersecurity, for example, and learn about emerging cyber threats. Or you could focus more on specific elements of computer science that appeal to your interests and passions, such as game development.
Who It’s For
The BSc in Computer Science program can suit a whole range of prospective applicants and should appeal to anyone with an interest or passion for computing and a desire to pursue a professional career in this field. Whether you’re seeking to enter the world of software development, user experience design, data science, or another related sector, this is the course to consider.
In addition, thanks to OPIT’s engaging, flexible, and exclusively online teaching and learning systems, this course can appeal to people from all over the globe, of different ages, and from different walks of life. It’s equally suitable for recent high school graduates with dreams of making their own apps to seasoned professionals looking to broaden their knowledge or transition to a different career.
The Value of the BSc in Computer Science Course at OPIT
Plenty of universities and higher education establishments around the world offer degrees in computer science, but OPIT’s program stands out for several distinctive reasons.
Firstly, as previously touched upon, all OPIT courses are delivered online. Students have a schedule of live lessons to attend, but can also access recorded content and digital learning resources as and when they choose. This offers an unparalleled level of freedom and flexibility compared to more conventional educational institutions, putting students in the driving seat and letting them learn at their own pace.
OPIT also aims not merely to impart knowledge through lectures and teaching, but to actually help students gain the practical skills they need to take the next logical steps in their education or career. In other words, studying at OPIT isn’t simply about memorizing facts and paragraphs of text; it’s about learning how to apply the knowledge you gain in real-world settings.
OPIT students also enjoy the unique benefits of a global community of like-minded students and world-leading professors. Here, distance is no barrier, and while students and teachers may come from completely different corners of the globe, all are made to feel welcome and heard. Students can reach out to their lecturers when they feel the need for guidance, answers, and advice.
Other benefits of studying with OPIT include:
- Networking opportunities and events, like career fairs, where you can meet and speak with representatives from some of the world’s biggest tech brands
- Consistent support systems from start to finish of your educational journey in the form of mentorships and more
- Helpful tools to expedite your education, like the OPIT AI Copilot, which provides personalized study support
Entry Requirements and Fees
To enroll in the OPIT BSc in Computer Science and take your next steps towards a thrilling and fulfilling career in this field, you’ll need to meet some simple criteria. Unlike other educational institutions, which can impose strict and seemingly unattainable requirements on their applicants, OPIT aims to make tech education more accessible. As a result, aspiring students will require:
- A higher secondary school leaving certificate at EQF Level 4, or equivalent
- B2-level English proficiency, or higher
Naturally, applicants should also have a passion for computer science and a willingness to study, learn, and make the most of the resources, community, and support systems provided by the institute.
In addition, if you happen to have relevant work experience or educational achievements, you may be able to use these to skip certain modules or even entire terms and obtain your degree sooner. OPIT offers a comprehensive credit transfer program, which you can learn more about during the application process.
Regarding fees, OPIT also stands out from the crowd compared to conventional educational institutions, offering affordable rates to make higher tech education more accessible. There are early bird discounts, scholarship opportunities, and even the option to pay either on a term-by-term basis or a one-off up-front fee.
The Open Institute of Technology (OPIT) provides a curated collection of courses for students at every stage of their learning journey, including those who are just starting. For aspiring tech leaders and those who don’t quite feel ready to dive directly into a bachelor’s degree, there’s the OPIT Foundation Program. It’s the perfect starting point to gain core skills, boost confidence, and build a solid base for success.
Introducing the OPIT Foundation Year Program
As the name implies, OPIT’s Foundation Program is about foundation-level knowledge and skills. It’s the only pre-bachelor program in the OPIT lineup, and successful students on this 60-ECTS credit course will obtain a Pre-Tertiary Certificate in Information Technology upon its completion. From there, they can move on to higher levels of learning, like a Bachelor’s in Digital Business or Modern Computer Science.
In other words, the Foundation Program provides a gentle welcome into the world of higher technological education, while also serving as a springboard to help students achieve their long-term goals. By mixing both guided learning and independent study, it also prepares students for the EQF Level 4 experiences and challenges they’ll face once they enroll in a bachelor’s program in IT or a related field.
Here’s a quick breakdown of what the OPIT Foundation Program course involves:
- Duration: Six months, split into two terms, with each term lasting 13 weeks
- Content: Three courses per term, with each one worth 10 ECTS credits, for a total of 60
- Focus: Core skills, like mathematics, English, and introductory-level computing
- Format: Video lectures, independent learning, live sessions, and digital resources (e-books, etc.)
- Assessment: Two to three assessments over the course of the program
What You’ll Learn
The OPIT Foundation Program doesn’t intensely focus on any one particular topic, nor does it thrust onto you the more advanced, complicated aspects of technological education you would find in a bachelor’s or master’s program. Instead, it largely keeps things simple, focusing on the basic building blocks of knowledge and core skills so that students feel comfortable taking the next steps in their studies.
It includes the following courses, spread out across two terms:
- Academic Skills
- Mathematics Literacy I
- Mathematics Literacy II
- Internet and Digital Technology
- Academic Reading, Writing, and Communication
- Introduction to Computer Hardware and Software
Encompassing foundational-level lessons in digital business, computer science, and computer literacy, the Foundation Program produces graduates with a commanding knowledge of common operating systems. Exploring reading and writing, it also helps students master the art of communicating their ideas and responses in clear, academic English.
Who It’s For
The Foundation Year program is for people who are eager to enter the world of technology and eventually pursue a bachelor’s or higher level of education in this field, but feel they need more preparation. It’s for the people who want to work on their core skills and knowledge before progressing to more advanced topics, so that they don’t feel lost or left behind later on.
It can appeal to anyone with a high school-level education and ambitions of pushing themselves further, and to anyone who wants to work in fields like computer science, digital business, and artificial intelligence (AI). You don’t need extensive experience or qualifications to get started (more on that below); just a passion for tech and the motivation to learn.
The Value of the Foundation Program
With technology playing an increasingly integral role in the world today, millions of students want to develop their tech knowledge and skills. The problem is that technology-oriented degree courses can sometimes feel a little too complex or even inaccessible, especially for those who may not have had the most conventional educational journeys in the past.
While so many colleges and universities around the world simply expect students to show up with the relevant skills and knowledge to dive right into degree programs, OPIT understands that some students need a helping hand. That’s where the Foundation Program comes in – it’s the kind of course you won’t find at a typical university, aimed at bridging the gap between high school and higher education.
By progressing through the Foundation Program, students gain not just knowledge, but confidence. The entire course is aimed at eliminating uncertainty and unease. It imbues students with the skills and understanding they need to push onward, to believe in themselves, and to get more value from wherever their education takes them next.
On its own, this course won’t necessarily provide the qualifications you need to move straight into the job market, but it’s a vital stepping stone towards a degree. It also provides numerous other advantages that are unique to the OPIT community:
- Online Learning: Enjoy the benefits of being able to learn at your own pace, from the comfort of home, without the costs and inconveniences associated with relocation, commuting, and so on.
- Strong Support System: OPIT professors regularly check in with students and are on hand around the clock to answer queries and provide guidance.
- Academic Leaders: The OPIT faculty is made up of some of the world’s sharpest minds, including tech company heads, experienced researchers, and even former education ministers.
Entry Requirements and Fees
Unlike OPIT’s other, more advanced courses, the Foundation Program is aimed at beginners, so it does not have particularly strict or complex entry requirements. It’s designed to be as accessible as possible, so that almost anyone can acquire the skills they need to pursue education and a career in technology. The main thing you’ll need is a desire to learn and improve your skills, but applicants should also possess:
- English proficiency at level B2 or higher
- A Secondary School Leaving Certificate, or equivalent
Regarding the fees, OPIT strives to lower the financial barrier of education that can be such a deterrent in conventional education around the world. The institute’s tuition fees are fairly and competitively priced, all-inclusive (without any hidden charges to worry about), and accessible for those working with different budgets.
Given that all resources and instruction are provided online, you can also save a lot of money on relocation and living costs when you study with OPIT. In addition, applicants have the option to pay either up front, with a 10% discount on the total, or on a per-term basis, allowing you to stretch the cost out over a longer period to ease the financial burden.
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