EC-603-A Data Communication - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDifferentiate between serial and parallel data transmission. Provide examples where each is used.
   How to answer

   • Define serial vs parallel transmission
   • Compare on bits per clock, lines, speed, cost, skew/crosstalk
   • Give examples: serial - USB, RS-232, SATA; parallel - printer port, memory bus
   • Conclude use-case suitability
2. 7 Marks
   bGiven a binary sequence 10110011011001, illustrate how it would be encoded using unipolar NRZ, polar NRZ and bipolar NRZ encoding schemes.
   How to answer

   • State binary sequence 10110011011001
   • Show unipolar NRZ waveform levels
   • Show polar NRZ waveform levels
   • Show bipolar NRZ / AMI waveform with alternate mark inversion
3. 7 Marks
   aDescribe the three modes of data transmission: simplex, half-duplex and full-duplex. Provide an example of each.
   How to answer

   • Define simplex, half-duplex, full-duplex with direction capability
   • Explain channel usage and timing for each
   • Give example for each
   • Compare in table
4. 7 Marks
   bDraw the seven layers architecture of OSI model and explain how these layers interact with each other to facilitate network communication.
   How to answer

   • Draw 7-layer OSI stack from Physical to Application
   • State function of each layer briefly
   • Explain peer-to-peer interaction and encapsulation
   • Explain data flow via SAPs and interfaces
5. 7 Marks
   aWhat do you understand by Transmission Media? Give the differences between guided media and unguided media.
   How to answer

   • Define transmission media
   • Define guided and unguided media with examples
   • Compare on medium, propagation, interference, distance
   • Summarize selection criteria
6. 7 Marks
   bWhat are the benefits of using packet switching in modern networks? Discuss the difference between the virtual circuit and datagram approaches in packet switching?
   How to answer

   • List benefits of packet switching: efficiency, robustness, sharing
   • Define virtual circuit approach with setup phase
   • Define datagram approach with independent routing
   • Compare on ordering, reliability, overhead
7. 7 Marks
   aUsing the CRC-8 polynomial $x^8+x^2+x+1$, compute the CRC for the data byte 11010101. Show the division process.
   How to answer

   • State CRC-8 polynomial $x^8+x^2+x+1$ and binary divisor
   • Append 8 zeros to data 11010101 and perform modulo-2 division
   • Show division steps to obtain remainder
   • State final CRC code
8. 7 Marks
   bDescribe the Sliding Window protocol. How does it improve efficiency compared to Stop-and-Wait protocol?
   How to answer

   • Define Sliding Window with sender/receiver windows
   • Explain Go-Back-N / Selective Repeat operation
   • Compare utilization vs Stop-and-Wait idle time
   • Show efficiency improvement with pipelining
9. 7 Marks
   aGiven a data block, illustrate how Longitudinal Redundancy Check (LRC) can be used to detect errors. Show the process step-by-step.
   How to answer

   • Define LRC as block parity over rows/columns
   • Show arrangement of data block with parity bits
   • Demonstrate LRC calculation step-by-step
   • Explain error detection at receiver
10. 7 Marks
    bDiscuss the Fiber Distributed Data Interface (FDDI) its main features. How it provides fault tolerance and high-speed communication.
    How to answer

    • Define FDDI as fiber-optic token ring standard
    • List main features: 100 Mbps, dual ring, timed token
    • Explain fault tolerance via dual counter-rotating ring and wrap
    • Explain high-speed mechanisms
11. 7 Marks
    aCompare and contrast DQDB and SMDS in terms of their design, functionality and typical use cases in metropolitan area networks.
    How to answer

    • Define DQDB and SMDS for MAN
    • Compare design: dual bus vs connectionless service
    • Compare functionality and addressing/switching
    • Give typical MAN use cases for each
12. 7 Marks
    bDiscuss the role of Frame Relay in modern networks. How does it achieve efficient data transmission and what are its limitations compared to more recent technologies.
    How to answer

    • Define Frame Relay and its role in WAN
    • Explain virtual circuits, frame structure, no hop-by-hop flow control for efficiency
    • Discuss limitations vs MPLS/IP/Ethernet
    • Conclude migration to recent technologies
13. 7 Marks
    aProvide an overview of the TCP/IP protocol suite and its importance in modern networking.
    How to answer

    • Outline TCP/IP layers vs OSI
    • Describe key protocols per layer: IP, TCP/UDP, application protocols
    • Explain addressing, routing, end-to-end reliability
    • State importance for Internet and interoperability
14. 7 Marks
    bExplain the concept of distance vector routing. How does it determine the best path to a destination, explain with suitable example.
    How to answer

    • Define distance vector routing and Bellman-Ford basis
    • Explain exchange of vectors with neighbours and table update
    • Show best-path selection by minimum hop/cost with example
    • Mention count-to-infinity and split horizon
15. 14 Marks
    Write a short note on any two :

    1. a)Topology
    2. b)HDLC
    3. c)SONET
    4. d)Internetworking Devices
    How to answer

    • Select any two topics from Topology, HDLC, SONET, Internetworking Devices
    • For each: define, key features/types/frame/format
    • Give diagram or application where relevant
    • Conclude significance