Test Papers / Previous Question Papers of IGNOU CS09 Data Communications and Networking December 2005

ADCA / MCA (II Yr)
Term-End Examination

December, 2005

CS09 : Data Communications and Networking

Time: 3 hours
Maximum Marks: 75

1. (a) In most network, the datalink layer handles transmission eror by requesting damaged frames to be transmitted. If the probability of frames being damaged is P, what is the mean number of transmissions required to send a frame if acknowledgements are never lost. (6)

(b) Elaborate wavelength division multiplexing. (4)

(c) If the bit string 0111101111101111110 is bit stuffed. what is the output string ? Illustrate. (2)

(d) Explain the concept of transparent bridges. Where are they used ? (5)

(e) Make diagrams of manchester coding and differential manchester coding of bit stream : 100110010. (4)

(f) Answer the following questions with respect to Internet congestion control algorithm :
(i) Explain all the parameters used in the algorithm. (3)
(ii) Plot the congestion window as a function of the transmission number and explain the function of the algorithm. (6)

2. (a) Why does UDD exist ? Would it not have been enough to just let user processes send raw IP packets ? (5)

(b) A channel has a bit rate of 4 kbps and a propagation delay of 20 msec- For what range of frame sizes does stop and wait give an efficiency ol at least 50% ? (5)

(c) Explain the functioning of broadband and baseband coaxial cable. (5)

3. (a) What is the difference between p-persistent, non peristent and 1-persistent CSMA ? (6)

(b) Measurement of a Slotted ALPHA channel with an infinite number of users shows that 10% of slots are idle. (4)
(i) What is the channel load G ?
(ii) What is the throughput ?

(c) List IEEE 802.5 standards for token ring and differentiate. (5)

4. (a) What do you understand by Quality of Service parameters ? List any live QoS parameters of tansport layer. (5)

(b) Make the diagram oI TCP header and explain its various fields. (5)

(c) What is congestion ? Elaborate leaky bucket algorithm used for congestion control. (5)

5. (a) Discuss the functioning of Reverse Address Resolution Protocol. (5)

(b) Compute a multicast spanning tree for router C in the subnet below for a group with members at routers A, B, C, D, E, F, J and K. (5)
-----DIAGRAM-----

(C) Make the diagram of IP_v6 header and explain its various fields. (5)

6. (a) Is fragmentation needed in concatenated virtual circuit internets or only in datagram segments ? Explain. (2)

(b) A new virtual circuit is being set up in all ATM network. Between the source and destination hosts lie three ATM switches. How many messages will be sent to establish the circuit ? (3)

(c) Differentiate between broadcast routing and multicast routing. (5)

(d) Answer the following questions :
(i) A Class B network on the Internet has a subnet mask of 255.255.240.0. What is the maximum number of hosts per subnet ?
(2) (ii) The protocol field used in IP_v4 header is not present in the fixed IP_v6 header, Why not ? (3)