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

ADCA / MCA (II Yr)
Term-End Examination

June, 2000

CS09 : Data Communications and Networking

Time: 3 hours
Maximum Marks: 75

1 (a) Using the Nyquist theorem, calculate the sampling rate for the following analog signals: [8]

· An analog signal with bandwidth 2000 Hz
· An analog signal with frequencies from 2000 to 6000 Hz

(b) What is the minimum number of samples for PCM encoding if the frequency ranges from 1000 to4000Hz? [5]

(c) What is the difference between bit rate and baud rate? Give an example where both are the same. Give an example where they are different. [5]

(d) Show by calculation how many hosts per network each IP address class (A,B and C only) can have? [5]

(e) In two byte address fields what is the maximum number of permanent virtual circuits possible? What about a 3 byte address? [7]

2 Answer the following questions:

(a) Contrast the IEEE 802.3 frame with HDLC I-frame. [5]
(b) Contrast the IEEE 802.5 frame with HDLC I-frame. [4]
(c) Why is there no AC field in 802.3 frame? [3]
(d) What are the advantages of FDDI over a token ring? [3]

3 Compare and comment on the following :
(a) Ethernet, token ring and FDDI in terms of access method, address length, signaling, data rate and error control. [6]
(b) Transport and source routing bridge in terms of orientation, transparency, configuration, routing, locating, failures and complexity. [6]
(c) Datagram subnet and virtual circuit subnet in terms of effects of router failure and congestion control. [3]

4 (a) Describe the working principle, advantage and disadvantage of the following routing algorithms:
· Reverse path forwarding
· Multicast routing
Also describe various ways of pruning the spanning tree. [10]

(b) Comment on five important quality of service parameters defined by the ATM standard. [5]

5 Answer the following questions associated with congestion algorithms:

(a) Difference between token bucket and leaky bucket algorithms. [4]

(b) Describe all the parameters used in flow specification technique. [4]

(c) Rate based congestion algorithm in ATM. [7]

6 Discuss the following question related to the transport layer:

(a) Many features of the transport layer (e.g., flow control and reliable delivery) are also handled by the data link layer. Is this duplication of effort ? why or why not? [3]

(b) What are the problems with 2-way handshake in connect establishment and connection termination? How does 3-way handshake resolve it? Explain through diagrams. [6]

(c) Upward multiplexing and downward multiplexing. [6]