Indira Gandhi National Open University (IGNOU) 2005 Diploma Computer Applications CS09 Data Communications and Networking - - Question Paper

ADCA / MCA (II Yr)
Term-End exam

June, 2005

CS09 : Data Communications and Networking

Time: three hours
Maximum Marks: 75

Note : ques. No. one is compulsory. ans any 3 ques. from the rest.
1. (a) How has the PCM sampling time been set at 125 µ sec ? discuss the process. (5)

(b) A processo n Host t has been assigned port P, and a process on Host two has been assigned port Q. ls it possible for there to be 2 or more TCP connections ranging from these 2 ports at the identical time ? discuss. (4)

(c) Consider a half duplex point-to-point link using the stop and wait scheme. What is the effect online utilization if
(i) the message size is increased so that fewer messages will be required?
(ii) the number of frames are increased for a constant message size ?
(iii) the frame size is increased ? (5)

(d) PPP is based closely on HDLC, which has user bit stuffing to prevent accidental flag-bytes within the payload from causing confusion. provide 1 cause why PPP uses character stuffing instead. discuss your option of cause. (3)

(e) Differentiate ranging from ARP and RARP with an example of every. (4)

(f) provide 2 reasons, and explain, why network might use an error-correcting code instead of fault detection and retransmission. (5)

(g) Why is CSMA/CD not applicable to a wireless environment ? (4)

2. (a) What is the cause for using an encoding scheme in FDDI that is various from the 1 used in CSMA/CD ? discuss the FDDI token ring operation, with an example. (10)

(b) Why does ATM use small, fixed length cells ? (5)

3. (a) Consider the Internet congestion control algorithm.
(i) discuss all ihe parameters used in the algorithm. (3)
(ii) Plot the congestion window as a function of the transmission number, and discuss the function of the algorithm. (7)

(b) What is a subnet ? How do you implement subnetting? discuss this with an example. (5)

4. (a) Why is compression needed ? Compare the JPEG and MPEG formats, with explanation. (5)

(b) Write the shortest path routing algorithm, and discuss every stage. (10)

5. (a) discuss the subsequent in the situation of transport layer : (7)
(i) Addressing scheme
(ii) Flow control and Buffering schemes

(b) A channel has a bit rate of four kbs and a propagation delay of 40 m sec. For what range of frames does stop-and-wait provide an efficiency of at lowest 60 percent ? (8)

Earning:   Approval pending.