Congestion Detection Phase Phase-2

Duration: 4 min

This video lesson is available to enrolled students.

Return to /learn/GATE-GUIDANCE-BY-SANCHIT-SIR/computer-networks/tl-congestion-udp/congestion-control-policy/asset-congestion-detection-phase-phase-2 after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Discrete Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic
  2. DataBase Management System/DBMS: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control
  3. Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  4. Computer Architecture: Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design
  5. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  6. C Language: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  7. Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. Computer Networks: Introduction to CN, 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
  10. Theory Of Computation/Automata Theory: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  11. 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
  12. Engineering Mathematics: Permutation and Combination, Linear Algebra, Calculus, Probability, Statistics
  13. General Aptitude: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, 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, Mensuration and Geometry, Mental Ability, Arithmetic, Profit and Loss, Powers and Exponents (Surds and Indices), Average, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Syllogisms, Venn Diagram, Seating Arrangements, Blood Relations, Directions (Direction Test), Analogy, Algebra, Time and Work, Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Cubes & Dices, Ranking, Order and Sequence, Mixture and Alligation, Age Problems, Clock, Selection Decision Table (Decision Making), Data Arrangement
  14. English (Verbal Aptitude): Vocabulary, Noun, Subject Verb Agreement (Verb Noun Agreement), Adjectives, Tenses, Pronoun, Preposition, Direct and Indirect Speech, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Completion (Fill in the blanks), Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Correction (Error Correction), Verbal Analogy (Word Based Analogy), Conjunction, Interjection, Verb, Articles, Adverb, Modals, Sentence Construction
  15. Live Classes Recordings(Earlier Batch): GATE 2026 Live Class
  16. Full Mock Test:
  17. Previous Year Papers:
  18. GATE 2026 Counselling: Counselling and Guidance Sessions
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture segment covers Phase 2 of TCP congestion detection, focusing on the sender's reaction to receiving three duplicate acknowledgements. The instructor explains that this event indicates a weaker possibility of network congestion compared to a timeout, suggesting that a segment may have been dropped while later segments reached the receiver. The sender's reaction involves setting the slow start threshold to half of the current congestion window size, decreasing the congestion window to this new threshold, and resuming the congestion avoidance phase. The second half of the video uses a graph to illustrate TCP congestion window behavior over time, with red annotations highlighting fast retransmission points and ssthresh levels across multiple cycles of slow start, congestion avoidance, and fast recovery.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor presents a slide titled 'Detection On Receiving 3 Duplicate Acknowledgements,' explaining that this event suggests a weaker possibility of congestion in the network. The slide lists the sender's reaction: setting the slow start threshold to half of the current congestion window size, decreasing the congestion window to this new threshold, and resuming the congestion avoidance phase. The instructor begins drawing a red diagram on the right side of the slide to illustrate packet loss and retransmission, with underlined keywords like '3 Duplicate Acknowledgements' emphasizing the key concept.

  2. 2:00 – 4:01 02:00-04:01

    The video transitions to a graph showing TCP congestion window size over time, with the instructor using red annotations to highlight specific events. A red circle marks the 'fast retransmission' point, while horizontal red lines trace ssthresh levels across different time intervals. The graph displays multiple cycles of slow start, congestion avoidance, and fast recovery phases, with the instructor pointing to timeout events and explaining how window size increases during slow start and congestion avoidance before dropping upon packet loss.

The lecture progresses from conceptual explanation to graphical illustration of TCP congestion control. The first phase establishes the theoretical framework: three duplicate acknowledgements trigger a specific reaction involving threshold adjustment and window reduction. The second phase visualizes this behavior through a time-series graph, connecting the abstract rules to concrete window size changes. Key pedagogical elements include structured bullet points for reaction steps, hand-drawn diagrams for packet flow, and annotated graphs showing phase transitions. The central idea is that duplicate acknowledgements represent a milder congestion signal than timeouts, warranting less aggressive window reduction (halving ssthresh rather than resetting to 1 MSS).

Loading lesson…