Computer Networks Unit 3 Notes

CS602 Computer Networks Unit 3 notes and PYQ analysis for RGPV CSE 6th Semester. This unit covers MAC Sublayer, ALOHA, Slotted ALOHA, CSMA, CSMA/CD, CSMA/CA, Binary Exponential Backoff and IEEE 802 standards.

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Unit 3 Overview

Unit 3 focuses on the Medium Access Control layer. It explains how multiple devices share a common communication channel and how collision detection, collision avoidance and channel access protocols work.

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MAC Sublayer

Understand how MAC layer controls access to shared transmission medium.

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ALOHA Protocols

Learn Pure ALOHA, Slotted ALOHA, throughput and efficiency concepts.

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CSMA Protocols

Study CSMA, CSMA/CD, CSMA/CA and Binary Exponential Backoff.

Unit 3 Topics Covered

Complete syllabus-based topics of CS602 Computer Networks Unit 3.

MAC Sublayer

Functions, responsibilities and importance of Medium Access Control sublayer.

Pure ALOHA

Random access protocol, vulnerable time, throughput and limitations.

Slotted ALOHA

Improved ALOHA protocol using time slots to reduce collisions.

CSMA

Carrier Sense Multiple Access and its persistent and non-persistent methods.

CSMA/CD and CSMA/CA

Collision detection in wired networks and collision avoidance in wireless networks.

IEEE 802 Standards

IEEE 802 LAN standards, Ethernet, wireless LAN and MAC layer standards.

Important Questions - Unit 3

These questions are useful for 7 marks and 14 marks answers in RGPV exams.

  1. What is MAC Sublayer? Explain its functions.
  2. Explain Pure ALOHA and Slotted ALOHA with suitable diagram.
  3. Derive the efficiency of Pure ALOHA and Slotted ALOHA.
  4. Explain how throughput is improved in Slotted ALOHA over Pure ALOHA.
  5. Explain CSMA protocol and its types.
  6. Explain Persistent and Non-persistent CSMA protocols.
  7. Explain CSMA/CD protocol with suitable diagram.
  8. Explain CSMA/CA protocol with suitable diagram.
  9. Explain Binary Exponential Backoff algorithm.
  10. Compare CSMA/CD and CSMA/CA.
  11. Explain collision-free protocols.
  12. Write short note on IEEE 802 standards.

CS-602 Computer Networks Unit 3 PYQ Analysis

RGPV B.Tech VI Semester Computer Networks previous year question analysis for Unit 3.

Unit 3 Main Topics

MAC Sublayer Pure ALOHA Slotted ALOHA CSMA CSMA/CD CSMA/CA Binary Exponential Backoff IEEE 802

Year-wise Unit 3 Questions Asked

Year Question Topic Importance
June 2025 Discuss different strategies used to avoid collisions in CSMA/CA. CSMA/CA ★★★★★
June 2025 What is Pure ALOHA and Slotted ALOHA? How is efficiency of Slotted ALOHA twice that of Pure ALOHA? ALOHA / Slotted ALOHA ★★★★★
June 2025 Explain CSMA/CD protocol in detail. CSMA/CD ★★★★★
Dec 2024 Explain Binary Exponential Back-off with suitable example. Binary Exponential Backoff ★★★★★
Dec 2024 Explain collision free protocol. Collision Free Protocol ★★★★
May 2024 Explain Pure and Slotted ALOHA and CSMA. ALOHA / CSMA ★★★★★
May 2024 Write short note on CSMA/CA. CSMA/CA ★★★★
May 2023 Explain the working principle of Slotted ALOHA with suitable sketch. Slotted ALOHA ★★★★★
May 2023 What is Limited Contention Protocol? Explain Adaptive Tree Walk Protocol. Limited Contention Protocol ★★★★
May 2022 A radio station is using 14.4 Kbps channel for message transmission using slotted ALOHA. Calculate maximum throughput. Slotted ALOHA Numerical ★★★★
Dec 2020 How is throughput improved in Slotted ALOHA over Pure ALOHA? ALOHA Throughput ★★★★★
Dec 2020 How performance is improved in CSMA/CD protocol compared to CSMA protocol? CSMA/CD ★★★★★

Topic Frequency Analysis

Topic Asked Times Years Priority
ALOHA / Slotted ALOHA 5 Times 2020, 2022, 2023, 2024, 2025 ★★★★★ Extremely Important
CSMA/CD 3 Times 2020, 2025 ★★★★★ Extremely Important
CSMA/CA 2 Times 2024, 2025 ★★★★★ Extremely Important
CSMA 2 Times 2024, 2025 ★★★★ Very Important
Binary Exponential Backoff 1 Time 2024 ★★★★ Very Important
Collision Free Protocol 1 Time 2024 ★★★ Important
IEEE 802 Standards Short Note 2023 ★★★ Important
MAC Sublayer Short Note 2020 ★★★ Important

Examiner Pattern for Unit 3

  • Unit 3 se examiner mostly ALOHA, Slotted ALOHA, CSMA/CD aur CSMA/CA poochta hai.
  • ALOHA ka throughput ya efficiency comparison repeatedly aata hai.
  • CSMA/CD wired networks aur CSMA/CA wireless networks ke comparison me poocha ja sakta hai.
  • Binary Exponential Backoff recent PYQ me aaya hai, isliye important hai.
  • IEEE 802 aur MAC Sublayer short notes me aa sakte hain.

Most Expected Unit 3 Questions

  1. Explain Pure ALOHA and Slotted ALOHA with diagram.
  2. Derive efficiency of Pure ALOHA and Slotted ALOHA.
  3. Explain how Slotted ALOHA improves throughput over Pure ALOHA.
  4. Explain CSMA/CD protocol with suitable diagram.
  5. Explain CSMA/CA protocol and collision avoidance strategies.
  6. Compare CSMA/CD and CSMA/CA.
  7. Explain Binary Exponential Backoff algorithm.
  8. Explain Persistent and Non-persistent CSMA.
  9. Explain collision-free protocol.
  10. Write short note on MAC Sublayer and IEEE 802 standards.

Final Prediction Scorecard - Unit 3

Topic Chance of Appearing
ALOHA / Slotted ALOHA95%
CSMA/CD90%
CSMA/CA90%
CSMA Protocols85%
Binary Exponential Backoff80%
Collision Free Protocol70%
MAC Sublayer65%
IEEE 802 Standards60%

Unit 3 Study Strategy

One Night Before Exam

  1. Pure ALOHA and Slotted ALOHA
  2. ALOHA throughput and efficiency
  3. CSMA/CD
  4. CSMA/CA
  5. Binary Exponential Backoff
  6. MAC Sublayer
  7. IEEE 802 Standards short note

Minimum Passing Strategy

Agar time bahut kam hai, to ALOHA, Slotted ALOHA, CSMA/CD aur CSMA/CA strong kar lo. In topics se Unit 3 ka question attempt karne ka chance sabse zyada hai.

10 CGPA Strategy

ALOHA efficiency derivation, CSMA/CD working diagram, CSMA/CA collision avoidance, Binary Exponential Backoff example aur IEEE 802 short notes sab prepare karo.

Most Expected RGPV Unit 3 Question Format

Q3

a) Explain Pure ALOHA and Slotted ALOHA. Derive the efficiency of Slotted ALOHA.

b) Explain CSMA/CD protocol with suitable diagram.

OR

a) Explain CSMA/CA protocol and collision avoidance strategies.

b) Explain Binary Exponential Backoff algorithm with suitable example.

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Detailed Notes

Complete Unit 3 notes for theory preparation.

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FAQs - CS602 Unit 3

What is Computer Networks Unit 3 about?

It covers MAC Sublayer, ALOHA, CSMA, CSMA/CD, CSMA/CA and IEEE 802 standards.

Which topic is most important in Unit 3?

ALOHA, Slotted ALOHA, CSMA/CD and CSMA/CA are the most important topics.

Is ALOHA numerical important?

Yes, Slotted ALOHA throughput and efficiency based numerical questions can appear in exams.