Working of Open System Interconnection OSI model

Duration: 7 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 2 | Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  3. Paper 2 | Computer Organization And Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Control Unit Design, Instr Formats & Modes, Programming the Basic Computer
  4. Paper 2 | Analog And Digital Communication: Introduction to Communication Systems & Random Signals, Analog Communication Systems, Information Theory & Digital Communication Fundamentals, Digital Modulation & Detection Techniques, Error Control, Synchronization & Multiple Access Techniques
  5. Paper 2 | Programming in C: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. Paper 2 | Data Structures And Programming: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  7. Paper 2 | Algorithms: Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  8. Paper 2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  9. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS
  10. Paper 2 | Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  11. Paper 2 | Information Systems and Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Paper 2 | Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware Basics
  13. Paper 2 | Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, CSS, XML, HTML5
  14. Paper 2 | Cyber Security And Emerging Technologies: Emerging Tech Trends, Internet of Things
  15. Paper 2 | Cloud Technology: Cloud Computing
  16. Paper 2 | Probability and statistics: Probability, Statistics
  17. Paper-1 English: Vocabulary, Preposition, Articles, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Cloze Test (Cloze Passage), Sentence Construction
  18. Paper 1 General Mental Ability & Logical reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Arithmetic, Speed Mathematics and Basic Mathematics, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Venn Diagram, Analogy
  19. Paper-1 General Knowledge & Current Affairs: State Wise GK, History, Geography, GK- Current Affairs, Static General Knowledge
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture introduces the OSI model's layered architecture, defining its seven ordered layers from Physical to Application. It explains vertical service dependencies and horizontal peer-to-peer communication, visually grouping the top three layers as software, the bottom three as hardware, and identifying Transport as the 'heart of OSI'. The core teaching focuses on peer-to-peer processes: data encapsulation where each sending layer adds its own header (AH, PH, SH, TH, NH, DH) to the message from above before passing it down. At Layer 1, the package is converted into a stream of bits for transmission across intermediate nodes to Device B. The receiving device then decapsulates the message layer by layer, unwrapping headers to deliver data back up to the application. Hand-drawn annotations emphasize specific layers and data flow.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor presents a slide titled 'Layered Architecture' listing the seven OSI layers. On-screen text states that each layer calls upon the services of the layer just below it, while 'layer x on one machine communicates with layer x on another machine' via peer-to-peer protocols. A diagram appears showing the seven layers stacked vertically, with arrows indicating sender and receiver flow. The visual categorizes the top three layers as 'Software Layers', the bottom three as 'Hardware Layers', and labels the Transport Layer specifically as the 'Heart of OSI'.

  2. 2:00 – 5:00 02:00-05:00

    The lecture transitions to a slide titled 'Peer-to-Peer Processes', using an animated diagram of Device A and Device B communicating through intermediate nodes. The instructor points to a diagram showing data encapsulation, where each layer adds its own header (AH, PH, SH, TH, NH, DH) to the data as it moves down the stack. The visual progression shows the step-by-step addition of headers, forming a growing package. The instructor explains that at Layer 1 (Physical), the entire package is converted to a stream of bits for transmission, while at the receiving machine, the message is unwrapped layer by layer.

  3. 5:00 – 7:08 05:00-07:08

    The instructor uses a stylus to draw red circles and arrows around the encapsulation diagram, highlighting headers (SH, TH) being added to data as it moves down the stack. The diagram shows Device A, intermediate nodes, and Device B, with on-screen text identifying 'Peer-to-peer protocol (7th layer)'. The instructor points to the Session and Network layers on both sides of the diagram, emphasizing that communication at the physical layer is direct, while higher layers require data to move down through the sender's stack and back up through the receiver's stack. Bullet points summarize the rules of peer-to-peer communication at different layers.

The lecture systematically builds understanding of the OSI model from its structural definition to its operational mechanics. It begins by establishing the seven-layer hierarchy and their vertical/horizontal relationships, using color-coded groupings (software/hardware/heart) to aid memorization. The central concept is encapsulation: the process where each layer adds its own header to the data from above. This is demonstrated through a step-by-step animated diagram showing headers (AH, PH, SH, TH, NH, DH) being prepended to the data as it travels from Application down to Physical. The physical layer's role in converting this package into a bit stream for transmission is highlighted as the critical transition point. The receiving process (decapsulation) is explained as the reverse, where headers are stripped away layer by layer. Hand-drawn annotations serve to reinforce specific layer interactions and data flow directions, making the abstract concept of peer-to-peer communication visually concrete for students.

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