Test Papers / Previous Question Papers of IGNOU CS09 Data Communications and Networking December 1998

ADCA / MCA (II Yr)
Term-End Examination

December, 1998

CS09 : Data Communications and Networking

Time: 3 hours
Maximum Marks: 75

1 (a) Is the Nyquist theorem true for all types of communication channels? [5]

(b) A cable TV system has a number of commercial channels, all of them showing programs and advertisement alternatively. What type of multiplexing is it? Justify your answer. [5]

(c) Write a C-program fragment to calculate CRC (cyclic redundancy code) for any message using polynomial generator x4+x3+x+1 using modulo –2 arithmetic. [10]

(d) A satellite channel of capacity of 1 Mbps uses 7-bit sliding window protocol. It uses 1000 bit frame which includes 30 header bits. The two-way propagation delay is 540 ms. Find out the bandwidth utilization of the channel. [10]

2 Discuss in detail the following approaches in the context of high speed modems:
(a) Quadratum Amplitude Modulation. [4]
(b) Trellis Coding [4]
(c) 32 & V.34 bits [4]
(d) MNP5. [3]

3 Discuss the following in the context of ATM switches:
(a) Input and output queueing at an ATM switch
(b) Functioning of the combined Batcher-Banyan 4 cell switch. [15]

4 (a) Describe the channel utilization versus load for various random access protocols? Where is the maximum? Explain your answer. [6]
(b) Discuss technologies (different types of wiring and hubs) in Fast Ethernet. [6]
(c) Why is the Manchester encoding not done in Fast Ethernet? [3]

5 (a) Where is the multicasting routing used? Describe its advantages and disadvantages. [4]
(b) Compute a multicast tree for router C in the subnet below for a group with members at routers A, C, D, E, F, I & K. [5]

(c) Describe a suitable congestion control algorithm with an example used for multicasting routing .

6 (a) How does window management take place in TCP? List a potential advantage when Nagle’s algorithm is used on a badly congested network. [6]

(b) Why is timer management much more difficult in the Internet’s transport layer? Discuss the algorithm proposed by Jacobson generally used in TCP for timer management. [9]