Note : Question number 1 is compulsory. Attempt any three questions from the rest.
Q.1. (a) Draw a spanning tree, a multicast tree for group 1 and multicast tree for group 2 of the following network.
(b) Given a 10 bit sequence frame: 101 11 01 1 0 and a divisor (polynomials) of 1101, find the CRC
(c) Sketch the Manchester and Differential Manchester coding of the following pattern 101110001110
(d) We want to digitize 4 kHz wide telephone channel. What is the minimum bit rate assuming 8 bits per sample ?
(e) Consider the following network. With the indicated link cost, use Dijkstra's shortest-path algorithm to compute the shortest path from G to all network nodes. Show the complete calculation.
(f) Using the RSA public key cryptosystem, if p = 7, q = 11, list 5 legal values for d.
(g) Consider an example of a Telenet session in which the user types a single character at a time and the server reacts to every keystroke. Calculate how many exchanges of IP packets and bytes will be needed. Show step by step calculation.
(h) What is the difference between an active and a passive intruder?
2. (i) Construct the Hamming code for the bit sequence : 11100010 and show the process of error correction at the 7th location.
(ii) What are the advantages of QAM over ASK and PSK? Draw a 16-QAM constellation (2 amplitudes and 8 phases) diagram.
(iii) With the help of of appropriadte diagrams explain IP addressing
Q.3. Differentiate between the following with appropriate examples/diaqrams
(i) Circuit switching and Packet switching
(ii) Propagation delay and Transmission delay
(iii) Upward multiplexing and Downward multiplexing
(iv) Open loop and Closed loop congestion control algorithms
Q.4 (i) If a binary signal is sent over a 4 kHz channel, whose S/N ratio is 20dB, can it carry 32 kbps data rate? Show relevant calcuations.
(ii) Explain a scheme of generation of digital signature.
(iii) Explain the operation of slow start congestion control algorithm in TCP with the help of a diagram.