Dec 2000

Question Paper of CS-09 – Data Communication & Network of Dec 2000 from IGNOU

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?

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

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

(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.

(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?

(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.

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

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

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

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

(iii) Discuss the FDDI token format.

4 Compare and comment on the following :

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

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

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.
(iii) How does window management take place an TCP List a potential advantage when Nagles algorthim is used on a badly congested network.

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