VTU Electronics and Communication Engineering (Semester 7)
Computer Communication Networks
June 2012
Total marks: --
Total time: --
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) With a neat diagram, explain the TCP/IP reference model.
10 M
1 (b) Explain in detail, the cable TV network used for data transfer.
6 M
1 (c) Calculate the minimum time to download the one million bytes of information using each of the following technologies:
(i) V.32 modem
(ii) V.32 bia modem
(iii) V.90 modem
4 M

2 (a) With a neat diagram of piggy backing in Go-Back-N ARQ protocol, explain the following:
(i) Frame structure of piggy backing
(ii) Types of events occurred in piggy backing
(iii) Advantages of piggy backing
10 M
2 (b) With a neat diagram, explain the different types of high level data link control (HDLC) frames.
6 M
2 (c) The following character encoding is used in a data link protocol:
A : 01000111 : B : 11100011 : FLAG : 01111110 : ESC = 111 00000. Show the bit sequence transmitted (in binary) for the four character frame : A B ESC FLAG when each of the following framing methods are used :
(i) Character count
(ii) FLag bytes with byte stuffing
(iii) Starting and ending flag bytes with bit stuffing
4 M

3 (a) With a suitable flow diagram, explain CSMA/CD protocol and discuss the frame transmission time.
8 M
3 (b) Explain the following controlled access methods:
(i) Reservation
(ii) Polling
(iii) Token passing
8 M
3 (c) Show that the throughput for the pure ALOHA is S=Ge-2G and maximum throughput Smax=0.184.
4 M

4 (a) With a neat diagram, explain 802.3 MAC frame format.
10 M
4 (b) Explain the following standard ethernet physical layer implementations.
(i) 10 base 5 : thick ethernet
(ii) 10 base 2 : thin ethernet
(iii) 10 base T : twisted pair ethernet
(iv) 10 base F: fiber ethernet.
10 M

5 (a) Explain the following in brief:
(i) Passive hubs
(ii) Active hubs
(iii) Bridges
(iv) Router
(v) Gateway.
10 M
5 (b) Explain virtual LAN system and how the membership is allocated in the V-LAN system.
10 M

6 (a) What are the difference between classful and classless addressing?
5 M
6 (b) What is network address translation (NAT)? Explain in brief.
5 M
6 (c) Draw the IPV4 datagram formats and explain its field.
10 M

7 (a) Explain the detail, the distance vector routing algorithm.
10 M
7 (b) Explain three different forwarding techniques.
10 M

8 (a) Explain in detail, user datagram protocol, UDP.
10 M
8 (b) Describe DNS in the internet.
10 M

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