ITT351: Computer Networks (Spring 2026)

Class Timings: Monday, Wednesday (Section A: 11:30-12:20 pm and Section B: 12:20-1:10 pm) 

  Tuesday (Section B: 11:30-12:20 pm and Section A: 12:20-1:10 pm) 

Venue: PF3

Piazza page: ITT351/home 

Course Overview

In this course, we will cover the basic concepts and details of network implementation. In particular, we will have an in-depth study of various TCP/IP model layers via a bottom-up approach.

Course Outline

• UNIT I - INTRODUCTION: History and development of computer networks, networks topologies. Layering and protocols.

• UNIT II - PHYSICAL LAYER: Different types of transmission media, transmission errors: attenuation, noise. Encoding (NRZ, NRZI, Manchester, 4B/5B, etc.).

• UNIT III - DATA LINK LAYER AND SWITCHING: MAC Layer: Aloha, CSMA, CSMA/CD, CSMA/CA protocols. Data Link Layer: Error detection (Parity, CRC), Sliding Window, Stop and Wait protocols. Framing, HDLC. Switching Theory: Circuit Switching, Message Switching, Packet Switching.

• UNIT IV - NETWORK LAYER: Network layer: Internet Protocol, IPv6, ARP, DHCP, ICMP, Routing algorithms: Distance vector, Link state, Metrics, Inter-domain routing. Subnetting, Classless addressing, Network Address Translation.

• UNIT V - TRANSPORT LAYER: UDP, TCP. Connection establishment and termination, sliding window revisited, flow and congestion control, timers, retransmission, TCP extensions, etc.

• UNIT VI - APPLICATION LAYER: Session, Presentation, and Application Layers. Examples: DNS, SMTP, IMAP, HTTP, etc.

References: We will refer to multiple books and lectures over the duration of this course some of them are as follows:

• Behrouz A. Forouzan, Data communications and Networking [BAF]

• JF Kurose, KW Ross, Computer Networking: A Top-Down Approach [KR]

• Larry Peterson and Bruce Davie, Computer Networks, A Systems Approach [PD]

• William Stallings, Data & Computer Communications [WS]

• Sandip Chakraborty, Soumya Kanti Ghosh, Computer Networks and Internet Protocol (NPTEL Course) [NPTEL]

• Aaron Balchunas, CCNA Guides [AB]

• Ajit Pal, Data Communications (NPTEL Course) [AP-NPTEL]

Grading Policy:

• Major exam - 50%

• Mid-Term exam - 26%

• Assignment-based quizzes - 8%

• General quizzes - 8%

• Tutorials - 8%

Tutorials (To be submitted on Gradescope) 

1. Tut 1 (Access control)

2. Tut 2 (Flow control)

3. Tut 3 (Framing, switched networks)

4. Tut 4 (IP addressing)

5. Tut 5 (Routing)

6. Tut 6 (Routing Table and IPV6)

Quizzes 

1. Quiz 1 (Assignment-based): Error detection and correction techniques. Date: 25 Feb

2. Quiz 2 (General quiz): Flow control. Date: 1 April

3. Quiz 3 (General quiz): IP Addressing. Date: 6 May

Here are the topics we covered in the class and the reference material we used.

1. Lec 1 (Feb 11): General introduction to the course, course outcomes, policies, and motivation. Recap of OSI model and TCP/IP model.

2. Lec 2 (Feb 16): Introduction to access control, motivation, random access protocols, pure Aloha. (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

3. Lec 3 (Feb 17): Pure and slotted Aloha analysis: throughput formula, maximum throughput. (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

4. Lec 4 (Feb 18): Motivation and working of CSMA, different persistent methods: 1-persistent, nonpersistent, p-persistent, motivation for CSMA/CD, minimum frame size, CSMA/CD algorithm, and its performance. (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

5. Lec 5 (Feb 23): CSMA/CA: need and motivation, collision avoidance strategies, Hidden and exposed node problem, RTS-CTS solution, NAV.  (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

6. Lec 6 (Feb 24): Controlled access methods - reservation, polling access method and token passing with examples. (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

7. Lec 7 (Feb 25): Channelization methods: FDMA, TDMA, CDMA - basic idea, working, properties of codes, generation of codes using Walsh tables. (Main source: Chapter 12 [BAF]) (Extra Source: Lec 25-27 [AP-NPTEL])

8. Lec 8 (Mar 9): Flow control and error control (ARQ), connection-oriented and connectionless protocols, piggybacking, FSM approach for protocols, Noiseless channel protocols - simple.  (Main source: Chapter 11 [BAF],  Chapter 11 [BAF 5th edition])

9. Lec 9 (Mar 10): Noiseless channel protocols - stop and wait, use of sequence number, sliding window. Protocols for noisy channels - Stop and Wait ARQ, FSM approach, flow diagram. (Main source: Chapter 23 [BAF 5th edition])

10. Lec 10 (Mar 11):  Efficiency and link utilization, bandwidth-delay product, need for pipelining, Go Back N ARQ - basic idea, sequence and ACK numbers, sender and receiver window size, timers, FSM approach, flow diagram. (Main source: Chapter 23 [BAF 5th edition])

11. Lec 11 (Mar 16): Selective repeat - sender and receiver window size, ACKs and timer, working, FSM approach, flow diagram. (Main source: Chapter 23 [BAF 5th edition])

12. Lec 12 (Mar 17): Link utilization and throughput of stop and wait and sliding window protocols with numericals. (Main source: Chapter 23 [BAF 5th edition]).

13. Lec 13 (Mar 18): Framing: fixed and variable-size, character-oriented protocols, byte or character stuffing, bit-oriented protocols, bit stuffing; HDLC protocol: configuration modes. (Main source: Chapter 11 [BAF])

14. Lec 14 (Mar 23): HDLC protocol: configuration modes, types of frames: information, supervisory, unnumbered and their associated control fields, PPP basics, frame. (Main source: Chapter 11 [BAF])

15. Lec 15 (Mar 24): PPP components, authentication protocols: PAP, CHAP, MAC address. Switched communication networks, motivation, and types, circuit-switched networks. (Main source: Chapter 11, 8 [BAF])

16. Lec 16 (Mar 25): Circuit-switched networks, Message-switched networks, Packet switching - basic idea, types. (Main source: Chapter 11, 8 [BAF])

17. Lec 17 (Mar 30): Virtual-circuit switching - overall idea, setup phase, data transfer and teardown phases, performance, delay and applications, MPLS basic idea. (Main source: Chapter 8 [BAF], Chapter 18 [BAF 5th edition])

18. Lec 18 (Apr 1): Datagram switching - overall idea, working, efficiency, and total delay with pipelining, finding optimum packet size. (Main source: Chapter 8 [BAF], Chapter 18 [BAF 5th edition])

All the best for the Mid-term exams!

19. Lec 19 (Apr 17): Introduction to the network layer, IP addressing, IPv4 address, hierarchy in addressing, basics of classful addressing, subnet mask, classful addressing - possible number of networks and hosts per network that can be configured, introduction to classless addressing and CIDR notation. (Main source: Chapter 19 [BAF], Chapter 18 [BAF 5th edition])

20. Lec 20 (Apr 20): Revisit classful and classless addressing, special addresses and their use, private addresses: their range, use, basic idea of network address translation (NAT). (Main source: Chapter 19 [BAF], Chapter 18 [BAF 5th edition])

21. Lec 21 (Apr 21): Motivation behind subnetting and supernetting, questions on subnetting (Class A, B, C). (Chapter 19 [BAF], Chapter 18 5th Edition [BAF]) (CCNA IPV4 addressing and subnetting [AB])

22. Lec 22 (Apr 22): Variable-length subnet mask: motivation, examples. Hierarchical addressing with subnetting. (Chapter 19 [BAF], Chapter 18 5th Edition [BAF]) (CCNA IPV4 addressing and subnetting [AB]).

23. Lec 23 (Apr 27): Alternate methods to find Network ID, Broadcast ID for a given host, examples, Network address translation, motivation, problems, single-level translation, translation based on port number and IP address. (Main source: Chapter 19 [BAF], Chapter 18 [BAF 5th edition])

24. Lec 24 (Apr 28): Address aggregation or supernetting, use of forwarding or routing tables, longest mask matching, End-to-end forwarding of IP packets: within local network and across the network boundary, use of switch, ARP, and Routing tables. (Main source: Chapter 18, 20 [BAF 5th edition])  (Extra Source: Packet Traveling)

25. Lec 25 (Apr 29): Data delivery in networks, how routing tables work, default route. Basics of routing, types of routing: static, default, dynamic, Internet and autonomous systems, Intradomain and interdomain routing protocols - classification, overall idea. (Main source: Chapter 22 [BAF], Chapter 20 [BAF 5th edition])

26. Lec 26 (Apr 30): Distance vector routing: basic idea, initialization, sharing, updating, periodic and triggered updates, two-node instability problem and solutions. (Main source: Chapter 22 [BAF], Chapter 20 [BAF 5th edition])

27. Lec 27 (May 4): Two-node instability problem and solutions, three-node instability, RIP, examples of distance-vector routing. (Main source: Chapter 22 [BAF], Chapter 20 [BAF 5th edition])

28. Lec 28 (May 7): Link-state routing: overview, idea, generation and dissemination of LSPs, shortest-path tree formation via Dijkstra's algorithm, routing table formation, examples. (Main source: Chapter 22 [BAF], Chapter 20 [BAF 5th edition])

29. Lec 29 (May 8): Need for path-vector routing, Path vector routing steps: Initialization, sharing and updating, loop prevention, policy routing, metrics, and BGP. IP Supporting protocols - ICMP, IGMP, ARP, RARP, Dynamic address assignment using DHCP.  (Main source: Chapter 22 [BAF], Chapter 18, 20 [BAF 5th edition])

30. Lec 30 (May 11): Dynamic address assignment using DHCP, message format and DHCP operation, Introduction to IPV6, motivation and characteristic features, IPV6 representation: abbreviation, zero compression, and mixed notation, special IPV6 addresses, IPV4 compatible formats: compatible, mapped. (Main source: Chapter 19 [BAF], Chapter 22 [BAF 5th edition])

31. Lec 31 (May 12): Global unicast address, generating interface ID using link-layer address, private addressing: site-local and link-local, multicast address. IPV4 header format, function of different fields in the header, and why we require all of them, example questions about IPV4 header. (Main source: Chapter 19, 20 [BAF], Chapter 19, 22 [BAF 5th edition])

32. Lec 32 (May 13): IPV4 function of different fields in header, need for fragmentation, Maximum transfer unit (MTU), How is fragmentation done? Fragmentation fields: identification, flags, fragmentation offset. Fragmentation examples. (Main source: Chapter 20 [BAF], Chapter 19, 22 [BAF 5th edition])