Login with Facebook
Close

What is the 7 layers of OSI model?

How is it possible to make so many machines communicate? How not to get lost in this maze of information? At this step, we will see this first trying to understand how the Internet was created and what standards were implemented to orchestrate this news ball. Here, you will learn what is the 7 layers of OSI model.

How to communicate?

Imagine being able to communicate anytime, whenever you want, with anyone in the world! This is what the Internet offers us. It is not easy to express yourself when we are a small group of 10 people, difficult when we are 100, and almost impossible when we are 1000. Therefore, the Internet offers to take up the challenge of communicating all together at the same time. Time, whenever we want. Of course, to achieve this feat, it was necessary to create a complex communication system allowing the machines to talk to each other.

But how did this model of communication come to be?

Well, the easiest way is to start with what we already know about communication. And that anyone can do it!

Let's do a little inventory of the means of communication:

- the speech ;

- the phone ;

- the mail ;

- the carrier pigeon;

- etc.

Let us now try to understand, among these means of communication, what we need to communicate.

For speech, we need:

- an issuer;

- a receiver;

- a transmission medium (air).

It's a bit the same for the telephone except that we need a complementary element, which is the intermediary between speech and electronics. Speech is transformed into electrical signals. They arrive on the receiver side, and then they are again transformed into speech. We know that there is an encapsulation of information.

We find this encapsulation system in the mail, for which we need:

- an issuer;

- a receiver;

- a transmission medium (the letter);

- a container (the envelope);

- An intermediary (the post office).

Thus, we begin to understand what it takes to communicate. Now, will this be applicable to computers? How are we going to all talk at the same time? Will we be able to communicate with the other side of the world instantly?

Later, we will see how the researchers managed to move from the principles of human communication to the principles of communication for computers. They have thus grouped all of their research and results in a standard that people connecting to the Internet will have to meet.

What is OSI MODEL?

The OSI (Open System Interconnection) model was created by the International Organization for Standardization (ISO) as a reference model for open communication through various technical systems. This program makes perfect sense if we take into account the beginnings of the Internet. Indeed, at the end of the 1970s, the main players in new technologies were confronted with the multitude of existing models of machines. Few manufacturers then thought about their networking and hardly cared about their adaptability to each other. The Internet has led to the establishment of compliance standards between computers in order to allow common communication.

The OSI model is the result of an attempt at standardization. It draws a conceptual framework for the design basis of communication standards between different computers.

The OSI model divides the complex process of communication into seven layers. That’s why it is called a layered model. Communication between two systems requires that each layer respect a task. We can cite, for example, the control of communications, the addressing of the target system, or the translation of data packets into physical signals. Yet this model only works if all the systems participating in the communication stick to the rules. We see that the latter are found in protocols that are configured for specific layers or that intervene between layers. However, the ISO reference model is not a concrete network standard. Instead, it describes what processes must be regulated for communication to work over a network in abstract form.

Layers of an OSI model

Communication between the two computers may be trivial. Indeed, when transferring data via a network, it is normal that many actions are controlled and that they meet certain requirements in terms of the trust, security, or even integrity. This practice of dividing communication into layers has since proven its worth. Thus, each layer leads to a domain of well-defined functions. A standard usually covers only part of the layered model. It is built hierarchically. Bypassing through an interface, each layer uses another located below and is, in turn, available to the other layers of the higher level. This principle has two decisive advantages:

- The functions and requirements that must be mastered fulfilled within a layer are clearly defined. The standards for each layer can be developed independently of each other.

- Since the individual layers are clearly separated, changes to one standard have no influence on the processes that work on other layers.

With regard to their tasks, these seven layers of the OSI model are divided into two groups: that oriented application and those oriented communication. These processes that occur at each layer can be understood by the example such as the transfer of an email from a computer to the email server:

Application-oriented layers

The upper layers of the OSI reference model are described as application-oriented layers. They have three names: "application," "presentation," and "session."

- Layer 7 called application: this area of ​​the OSI model has direct contact with applications such as e-mail programs or the browser. This is where the data inputs and outputs take place. The application layer creates the link with the other hardware (or lower) layers of the OSI model and initiates the application functionalities. To prove this point, let's take the example of email forwarding: a user writes a message in his computer's email program. This email is transferred as a data packet in the application layer. At the same time, other information is added to the email data in the form of an application header. We then speak of encapsulation. This header contains, among other things, the information that it is data from an e-mail program. In addition, the protocol defines that the transfer of the email is used on the application layer (in the case of a normally SMTP email).

- Layer 6 is known as presentation: one of the common tasks of network communication is to ensure that data is transmitted in a standard format. The presentation layer presents local programs converted to standard formats. If we take the above example, it is layer six that defines the transferred message's presentation. In addition, the data packet is supplemented with a presentation header. This contains information on the email code, the format of the attachments, and how it is compressed or even encrypted (e.g., SSL / TLS). This is how we see that the target system interprets the format of an email and that it is transmitted accordingly.

- Layer 5 called session: The session layer's central task is the management of the link between the two systems. We then speak of communication-oriented layers. This is where these specific control mechanisms take effect. They are the ones that regulate binding, maintaining connection, and disconnection. Regarding this communication command, other information is added to the email data transmitted via a session header. Most common application protocols such as SMTP or FTP take care of the sessions themselves or are like HTTP independent. The TCP / IP model, which competes with the OSI model, sums up OSI 5, 6, 7 into an application layer. Other standards that act on Layer 5 are NetBIOS, Socks, and RPC.

Communication-oriented layers

Four communication-oriented layers follow on from the three application-oriented layers of the OSI model. These four layers are: “transport,” “network,” “link,” and “physical.”

- Layer 4 called transport: the transport layer serves as a link between the application and communication-oriented layers. At this level, the OSI model creates the logical connection or the transmission channel between the communicating systems. In addition, certain information must be added to the data of the email. The data packet that has already been added to the Application Oriented Layer header is supplemented by a Layer 4 transport header. This is where standardized network protocols such as TCP come in. Additionally, ports are defined on the transport layer, where applications are managed on the target system. It is on layer four that the data packet is assigned to a particular application.

- Layer 3 is known as a network: Layer 3 allows data transmission over the Internet and, more particularly, the logical addressing of terminals. A unique IP address is assigned on Layer 3. A network header is added to the data packet that contains information about routing and flow control. Computer systems use Internet standards such as IP, ICMP, X.25, RIP, or even OSPF. As far as email exchanges are concerned, TCP generally intervenes before IP.

- Layer 2 is known as the link: the link layer performs functions such as fault detection, troubleshooting, and flow control and aims to avoid transfer errors. In addition, the data packet, which includes the application, presentation, session, transport, and network headers, is surrounded by a header and a link path. Finally, it is on layer two that the physical addressing takes place.

- Physical layer 1: This is where the bits of a data packet is converted into an appropriate physical signal to a transmission medium. This signal can be transmitted via copper wire, an optical fiber, or in the open air. The transmission medium interface is defined by protocols and standards such as DSL, ISDN, Bluetooth, USB, or Ethernet (both physical layers).

Encapsulation and decapsulation

The data packets pass through each layer of the OSI model, on the sending system, and finally, the target system. All the terminals encountered are configured for layers 1 to 3. The email (above-mentioned example) passes as a physical signal first through the router, before continuing its route on the Web. It is located on layer 3 of the OSI model and, therefore, only processes information from the first three layers. Layers from 4 to 7 are not taken into account. In order to receive access to the necessary information, the router must first decompress the encapsulated data packet. This is called decapsulation. In this case, the layers of the OSI model are executed in reverse order.

First, you need to decode the signal on the physical layer. Next, the Layer 2 MAC addresses and the Layer 3 IP address and routing protocol should be read. With this information, the router is able to make the decision to forward the email. The data packet can then be encapsulated and transmitted based on the information obtained at the next station on the way to the target system. Typically, multiple routers are involved in a data transfer. The described process of decapsulation and encapsulation times out until the data packet arrives as a physical signal to the actual target (e.g.OSI model, a mail server). The data packet is again decapsulated here by traversing the OSI model layers from layers 1 to 7. The email sent via the messaging client arrives at the server where another client is ready to retrieve it.

Author: Vicki Lezama


Need a custom
essay?

We will write it for you.
Order now

Free Essay Examples

Free essays:

All you need to know about Neuroendocrinology
All you need to know about Big data management
All you need to know about digital special effects
All you need to know Technical Writing?
Basics the Game Theory in Cryptoeconomics
Business innovation ideas for making money
Biosensors for cancer diagnosis
Business Analysis: Pricing strategies and Demand Curve
Cognitive Computing- How does Cognitive Computing work?
Consciousness: characteristics and peculiarities
Conservation Economics
Cybersecurity in business: challenges, risks, and practices
Demographic trends and how they affect Economic Growth
Dance as an art form and entertainment
Discrimination Economics
Determinants of Wages
Everything you need to know about short-term memory
Economic and Policy Impacts of Demographics
Ethics: an essay on the understanding of evil
Emotions: what are they? Theories explained
Factors of Demographic Data Collection
Factors Affecting Purchasing Behavior
Financial Statement Analysis
Factors Influencing Interest and Exchange Rates
Government's Intervention in The Labor Market
Guide on the Pathways of the nervous system
Game theory in microeconomics
Globalization: definition, causes, social impact and risks
How Relativism Promotes Pluralism and Tolerance
How to use the audience’s feedback to write a news report
History of silent cinema
How news report can be strengthened through multimedia
Introduction to Population Problems
Imperfect Information and Asymmetric Information
Imperfect Information in Insurance
Introduction to Labor Markets
Journalism: What is News?
Journalism: Broadcast media and Television Presenters
Journalism: Sources of News
Journalism and Law
Key Determinants of National Income
Key Factors That Affect Pricing Decisions
Kinetic models in biology and Related fields
Know about the different forms of traditional African dances
Latest technology trends
Latest dance trends
Magnetoencephalography (MEG)
Microeconomic Analysis to the Demand for Labor
Neuromuscular disorders
National Economies, Fluctuation, and Responses to Fluctuations
Neurotransmitters: what they are and different types
Nanomedicines to target tumors
Objections to utilitarianism
Organizational motivation and its effects
Overcoming Hiring Challenges for Nonprofit Organization
Population Demographics
Recurrent neural networks (RNN) for speech detection
Russian School of Mathematics
Research and Development
Risk Sharing in Insurance and Asset Markets
Stochastic optimization methods in deep learning?
Structure of the nervous system
Structure of a Corporation
Schizoaffective disorder: how to live better with it
The climate change denial
The techniques of basic cinematography
The Endosymbiotic Theory
The Role of Internal Audit in Corporate Risk Management
Unions
Unemployment
Utilitarianism Vs. Kantianism
Understanding Auctions and Auction Theory: Part 2
Various theoretical perspectives of sociology
Virtual reality, what it is and how it works
What are the linear models in machine learning?
What is Convolutional Neural Network
4 Facts about Origin of Mathematics!
5 techniques to create an animation
10 emerging technologies according to World Economic Forum
10 strategies to maximize corporate profits
3d Model Of Building
6 Medical Technologies that revolutionized the healthcare in 2020
All you need to know about the ACA Code of ethics
Architecture and Democracy: An Introduction
Architecture and Democracy: Democratic Values
Architecture and Democracy: Democratic Procedures
All You Need to Know About a Synthesis Essay
An essential guide to understanding Film Theory
Application of Artificial Intelligence in Cyber Security
Applications of electrical engineering
Augmented reality: what it is, how it works, examples
Advantages And Disadvantages Of Social Networking
All you need to know about Cryptography
Applications of astrophysical science
All you need to know about architecture engineering
Applications of geological engineering
Artificial intelligence and medicine: an increasingly close relationship
An insight into Computational Biology
ACA code of conduct
A Rose for Emily
Applications of Mathematics in daily life
Architecture mistakes to avoid
All you need to know about Toxicology
All you need to know about Holistic Medicine
All you need to know about linguistics
An introduction to Linguistics and its subfields
All you need to know about Anxiety disorder
All you need to know about Drones
A Brief Insight into Political Science
Assumptions related to feminism
All you need to know about Byzantine emperors
All you need to know about labour economics
An insight into xenobots -the first-ever robots
An ultimate guide about Biomaterials
A Comprehensive Introduction to the Mona Lisa
Analysis methods of Transport through biological membranes
An ultimate guide about biochemical reactions
Analysis of brain signals
Artificial Gene Synthesis
Application to synthetic biology of CAD methods
All you need to know about metabolic pathways
Applications of BIOMEMS
All you need to know about the epidemiology
Asian vs. western leadership styles
All you need to know about Smart prosthesis
Analysis of Economy: Output of Goods and Services (GNP), and GDP on Economic success
A Guide to Pricing Strategies
An Overview Of Economic Studies
Analysis of Fiscal and Monetary Policies
Analysis of Business Cycles
Analysis of Consumption and Investment
A Look into Regression Analysis
Analysis of Household's Consumption and Savings Behavior
All you need to know about Capital Budgeting
All you need to know about risk management
Art looted in wartime.
Appropriate use of Data in Economics
All you need to know about reaction kinetics?
A historical overview of Financial Crises
All you need to know about management discipline?
An insight into the error-correction models
All you need to know about Data visualization
All you need to know about Work-family balance
All you need to know Technical Writing?
All you need to know about digital special effects
All you need to know about Big data management
All you need to know about Neuroendocrinology
How to Write a Personal Essay
Housing Needs in America
How to Write a Description Essay
How to Create an Excellent Scholarship Essay?
How to write a cause and effect essay
How to Hire the Best Essay Writing Service Provider?
How to Write a College Application Essay?
How to get the most out of your English lectures
How to write Expository Essay
How to succeed in your psychology class?
How to Write an Academic Essay in the Shortest Time?
History of Journalism
How Different Sectors are Using Artificial intelligence (AI)
How to write an informative essay
How to deliver persuasive essays?
How to Give a Convincing Presentation
How to write an essay on leadership?
Historical Art Still Around Today
Humanoid robot: what it is, how it works and price
History of Chemistry
Healthcare Advanced Computer Power: Robotics, Medical Imaging, and More
Healthcare AI: Game Changers for Medical Decision-Making and Remote Patient Monitoring
How to understand different types of English
How to Cope with Chronic Pain
How African American choreographers and dancers have influenced American dance
How mobile robot can do in logistics or in production
How To Become a Successful Entrepreneur
History of the Philosophy of Feminism
How is the climate changing?
How to Track Your Content Marketing ROI
How to Gun control In the USA?
Historical and contemporary role of labour in the modern world
How breast cancers are classified?
How the cells of our body communicate?
How the Lymphatic System Works?
How Digestive System Works
How to complete your capstone projects effectively?
How to write a research project
Healthcare technologies that help patients with better self-management
How to choose the topic of the senior capstone project
How to make your business survive at economic crisis
How can immigrants blend in the American society?
How does the economics of war affect society?
Hate speech on social media.
How to Build an Economic Model
How to start a healthcare startup?
How can financial illiteracy harm you?
How cancer is developed - Cancer biology
How to define the Enterprise Value
How to conduct economic research?
How women can manage sexual harassment
How to use quotes in your news reports?
How news report can be strengthened through multimedia
History of silent cinema
How to use the audience’s feedback to write a news report
How Relativism Promotes Pluralism and Tolerance
Introduction to Urban Studies
Importance of dance in education
InMoov: how to build an open source humanoid robot
Importance of KYC verification to making the Blockchain secure
Importance of Rhythm
Importance of dance student evaluation
I/O control methods -types and explanations
Identity theft: what to do?
Introduction to Utilitarianism
Importance of 3d Modelling in Architecture
Importance of online journalism
Image processing in medical diagnosis
Introduction to USA Politics
Introduction to Comparative Politics
International Relations as a Major in Political Science
Importance of modern trade policy
Introduction to Journalism
Introduction to Writing a TV Script
Introduction of Microfabrication techniques
Introduction to Microeconomics
Interaction of Consumer and Firm Choices in Markets
Importance of corporate sustainability
Issues in International Monetary Macroeconomics
Introduction to Statistics and Data for Economics
Introduction to Data and Probability for Economics
Introduction to the Game Theory
Introduction to Econometrics
Introduction to Economic Information
Introduction to Market Equilibrium
Introduction to Economic Models and Application
Introduction to Empirical Research
Introduction to Econometric Data
Importance of Critical Thinking, Principles, and Goals
Introduction to Identification and Causal inferences
Introduction to Econometric Application
Intermediaries and Government in Financial Crisis
Importance and seven principles of quality management
Illiteracy in the USA
Introduction to Economics of Law
Introduction to Coase Theorem
Introduction to Social Choice and Incarceration
Intellectual Property and Product Liability
Investment in Human Capital
Introduction to Labor Markets
Imperfect Information in Insurance
Imperfect Information and Asymmetric Information
Introduction to Population Problems
The Looming Energy Crisis in America
Top benefits of performance-based engineering
The More Languages You Know, The More Times You Are a Man
Things to consider while writing an Argumentative Essay
Top Ways to Improve Your Academic Writing Skills
Tips to Excel in Creative Writing
The origins of films in the early 19th century
Top career options in Architecture
The Elevator Pitch
Top finance trends 2020
The basic Structure and functionality of robots
The Way to Success
The election system of the President in the United States of America
Two-party System in United States of America
Top trends in urban design
The history and theory of African American filmmaking
Top benefits of creative writing
Tinnitus Guide: Common Symptoms and Treatment Options
The language of dance
The digital image processing management
Top famous politicians of the World
Top methods of political science!
The history of the feminist movement
The blood flow in cardiovascular system - Biofluid Mechanics
The best of Leonardo Da Vinci
The Structure and Function of Macromolecules
The structure of cell: a research on the bricks of the human body!
Tissue and organ construction: Adhesion and recognition between cells
The kinetics of the transformation processes
The Modeling of Biological Systems
Tips for writing a great thesis statement
The Defense mechanisms against infections
The impact of the technological innovations in medicine
Top journalism trends to know about
The relation between mass media & politics
Theranostics: Diagnosis and Care through Nanoparticles
The practical Applications of X-rays
The applications of Ultrasound in medicine
Transfer mechanisms of genetic information in Bacteria
The regulation of cellular metabolism in the diagnosis
The Principles of MRI Contrast agents
The technical basis of optical coherence imaging
The New Media: Emerging Trends
The Structure of Interest Rates and the Yield Curve
Technological perspectives and reflections of neural engineering
Types of bioreactors and their applications
The Role of Government Policy in Improving Economic Outcomes
Types of corporate responsibility
The Role of IMF in International Monetary Macroeconomics
Tools for investment decision making
The concept of Organizational Culture and its applications
The Conduct of Monetary and Fiscal Policy
The Basics of Financial Accelerator Models
Tips for labeling medical devices- Medical Entrepreneurship
The different medical imaging techniques
The Economics of Uncertainty – Introduction
Theories of Public Policy
The Game Theory in Social Media
The political theory of Thomas Hobbes
The Use of Law on Economics and Vice Versa
The Role of Internal Audit in Corporate Risk Management
The Endosymbiotic Theory
The techniques of basic cinematography
The climate change denial
What is a Definition Essay?
What are diagnostic essays?
What is the relation between art structural engineering?
What is a Narrative Essay
What are robotics and intelligence systems?
What are the benefits of studying health sciences?
What is artificial intelligence and why it matters?
What is comparative Literature?
Why study neuroscience
What is Wi-Fi and how does it works
What is French history famous for?
What are Humanistic Studies?
What is covered in Biophysics?
What is modern journalism?
What is Virtualization? Benefits & Applications
What are modern public relations?
What is plasma physics?
What is teacher preparation?
What is rapid prototyping for 3D printing?
What is contemporary European Politics?
Why should you learn American Ballet?
What is engineering physics?
What is the purpose of African American Literature?
Ways to learn the Rhythm
What is digital art used for?
What are Enzymes and how do they work
Who is the father of political science?
Why Study Political Science - Job?
What is the Philosophy of Feminism?
What is a quantum computer?
Ways B2B Startups Streamline Their Conversion Strategies
Why do biomedical signals need processing?
What are the long term effects of climate change?
Why study labour relations
What is Holoprosencephaly?
What is antisocial disorder?
What are the important principles of evolution?
What is the cytoplasm and its function?
What is biopolymers?
What Makes a Good Leader
Women empowerment in modern generation
What is the history of political thought?
What is Gene recombination
What is synthetic biology
What is business cost analysis?
What is Inflation
What are the consequences of unemployment?
What is lithotripsy and its types?
What is transition elastography?
What is the purpose of deep brain stimulation?
What is a Brain-Computer Interface (BCI)
What is neuroethics?
What is Market and Supply and Demand
What is optogenetics?
What are the techniques to record brain activity?
What happens if the interest rate increases?
What is immunotherapy?
What is the economic role of the financial market?
What are the factors behind illegal immigration?
What is the lymphocyte activation?
What is financial market and its types?
What is the structure of financial markets?
What are the methods of measuring business performance?
What is the Credit market?
What is business ethics and code of ethics
What are the Causes of financial instability?
What is MBA with Concentrations
What is regenerative medicine?
What is Population ecology?
What is Microfinance: evolution, and practices?
What is biotechnology and its applications?
What are Workplace diversity and its benefits?
What is the difference between a leader and a manager?
What Is Branding and best branding Business strategies?
Why are microelectronics important?
What are biologic drugs.
What is the Foreign Exchange market?
What is the role of scientific research in times of crisis?
What are the risks of international trade?
What is financial management?
What is gene therapy?
What is education economics?
What is regression analysis, and why should you use it?
What Is Technology Marketing And How Should It Work?
What is Management Accounting
What are the methods of valuation of companies?
What is Immune System and Immunotherapy?
What is big data analytics?
What is the 7 layers of OSI model?
What is Neuroplasticity?
What are Sculpture art and its types?
What are the different genres of films?
What is Transcranial magnetic stimulation (TMS)?
What is TES-Transcranial electrical stimulation?
What is Relativism?
What is Vaccine skepticism, and what to do about it?
What happens in the brain when learning?
What is the deep neural network?
What is Convolutional Neural Network
What are the linear models in machine learning?