Test Papers / Previous Question Papers of IGNOU CS09 Data Communications and Networking December 2000

ADCA / MCA (II Yr)
Term-End Examination

December, 2000

CS09 : Data Communications and Networking

Time: 3 hours
Maximum Marks: 75

1 (i) A television screen is composed of a grid of 525 lines by 700 columns (total of 367.500 pixels). A pixel can be black or white (1 or 0). Thirty complete screens (frames) are scanned in one second. What is the theoretical bandwidh required? [7]

(ii) Given a 10 bit sequence 1010011110 and a divisor 1011. Find the CRC. [4]

(iii) Given a remainder of 111, a data unit of 10110011 and a divisior of 1001, is there an error in the data unit? [4]

(iv) In a fibre optic cable, does the light energy from the source equal the light energy recovered at the destination? Discuss in terms of propagation media. [5]

(v) Given that the speed of light is 1,86,000 miles/second and a satellite is in geosynchronous orbit, how long would it take for a signal to go from the earth station to the satellite? [5]

(vi) What is the minimum number of samples for PCM encoding if the frequency ranges from 1000 to 4000 Hz? [5]

2 (i) Discuss how ATM connections are more efficient in their transmission than ISDN. [5]

(ii) Explain how ATM cells are routed through a network, highlighting why the cells always take a fixed route. [5]

(iii) Explain virtual channels, virtual paths and their uses in the context of ATM. [5]

3 (i) Discuss the token passing technique used in FDDI. [5]

(ii) Explain how FDDI allows robust networking after a cable break. [5]

(iii) Discuss the FDDI token format. [5]

4 Compare and comment on the following :

(i) Upward multiplexing and downward multiplexing [5]
(ii) Transparent and source routing bridge [5]
(iii) Ethernet and token ring in terms of access method, address length and signalling [5]

5 (i) Outline the operation of three-way handshaking [4]
(ii) Discuss IP address formats [5]
(iii) Describe the channel utilization vs load for various random access protocols. Explain your answer [6]

6 (i) Where is the multicasting routing used? Describe its advantages and disadvantages.
(ii) Describe a suitable congestion control algorithm with an example used for multicasting routing. [5]
(iii) How does window management take place an TCP List a potential advantage when Nagles algorthim is used on a badly congested network. [5]