NOTE: There are 9 Questions in all.
· Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.
· Any required data not explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or best alternative in the following: (2x10)
a. The art of rules that govern a communication exchange, are
(A) Media (B) Criterion
(C) Protocols (D) Multiple Access Choices
b. The end-to-end delivery of the entire message is the responsibility of the _____layer.
(A) Network (B) Transport
(C) Session (D) Presentation
c. The Nyquist theorem specifies the minimum sampling rate to be
(A) Equal to the lowest frequency of a signal.
(B) Equal to the highest frequency of a signal.
(C) Twice the bandwidth of a signal.
(D) Twice the highest frequency of a signal.
d. If the data unit is 111111 and the divisor 1010, what is the dividend at the transmitter?
(A) 111111000 (B) 1111110000
(C) 111111 (D) 1111111010
e. In which switching, each packet of message follows the same path from sender to receiver?
(A) Circuit switching
(B) The virtual circuit approach to packet switching
(C) Message switching
(D) The datagram approach to packet switching
f. In which case of ARQ, if a NAK is received, only the specific damaged or lost frame is retransmitted.
(A) Stop-and-wait (B) Go-Back-N
(C) Selective repeat (D) (A) and (B)
g. In which random-access method, stations do not sense the medium?
(A) ALOHA (B) CSMA/CD
(C) CSMA/CA (D) Ethernet
h. A routing table contains
(A) The destination network ID.
(B) The hop count to reach the network.
(C) The router ID to the next hop.
(D) Network topology.
i. Identify the class of IP address 4.5.6.7.
(A) Class A (B) Class B
(C) Class C (D) Class D
j. Which layer in ATM protocol has 53-byte cell as an end product?
(A) Physical (B) ATM
(C) Application adaptation (D) Cell transformation
Answer any FIVE Questions out of EIGHT Questions.
Each question carries 16 marks.
Q.2 a. Describe the ISO OSI reference model of a computer network. Discuss the function of each layer. (10)
b. Consider a telephone line of 4 kHz bandwidth. When the signal is 10 watts, the noise is 5 milli watts. What is the maximum data rate supported by this telephone line? (6)
Q.3 a. What is line coding? Explain the various line codes used in practice with relevant waveforms. (10)
b. Generate a CRC code for data word 110101010 using the divisor 10101. Check if there are any errors in the codeword obtained. (6)
Q.4 a. Describe SONET frame structure with suitable diagrams. (8)
b. Differentiate between
(i) IDU, SDU & PDU.
(ii) Confirmed and unconfirmed service. (4+4)
Q.5 a. Explain selective repeat ARQ protocol with a diagram. Compare the transmission efficiency of ARQ protocols with the performance curves. (8+4)
b. If the frame size is 960 bits on a satellite channel operating at 960 kbps, what is the maximum link utilization for stop-and-wait protocol? (Assume the propagation delay to be 270 milli sec) (4)
Q.6 a. Derive an expression for the throughput of a slotted ALOHA system and compare this with pure ALOHA system. (7+2)
b. Explain the basic CSMA-CA operation with a diagram. (7)
Q.7 a. How are routing techniques classified? Explain hierarchical routing with an example. (2+8)
b. Define Little’s formula and explain its significance in queuing models. (6)
Q.8 a. Discuss the structure of IP version 4 header format. (10)
b. Show by calculation
(i) How many networks each IP address (Class A, B) can have &
(ii) How many hosts per network each IP address (Class A, B) can have. (3+3)
Q.9 a. How does BISDN reference model is different from the OSI model? Explain with relevant figures. (10)
b. Describe classical IP over ATM model with a diagram. (6)