VTU Electronics and Communication Engineering (Semester 7)
Computer Communication Networks
December 2014
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) Discuss the TCP/IP model with functionalities of each layer. Consider source destination and intermediate modes for discussion.
10 M
1 (b) Explain the different services provided by telephone networks.
4 M
1 (c) Describe four levels of addressing used in internet (TCP/IP) with examples.
6 M

2 (a) What is HDLC? Explain different frame formats with control field used by HDLC.
10 M
2 (b) A system uses stop-and wait ARQ protocol. If each packet carries 2000bits of data, how long does it take to send 1 million bits of data if the speed is 2×108 m/sec? Ignore transmission, waiting and processing delays. We assume no data or control frame is lost or damaged. Repeat for go-back-n with window size=7
10 M

3 (a) What is channelization in the context of multiple access? What are various channelization techniques? Explain CDMA technique.
10 M
3 (b) Two station A and C are connected to a shared channel with data rate 10Mbps. The distance between A and C is 2500m and the propagation speed is 2×108 m/s. Station A starts sending a long frame at time t1=0; station C starts sending a long frame at time t2=3μsec. The size of the frame is long enough to guarantee the detection of collision by both stations. Find: (i) The time when station C hears the collision (t3) (ii) Time when station A hears the collision (t4); (iii) The number of bits A has sent before detecting the collision; (iv) The number of bits C has sent before detecting the collision.
10 M

4 (a) Explain the MAC frame format of IEEE802.3. Write a note on frame length.
10 M
4 (b) Explain the features of MAC sublayer and physical layer of Gigabit Ethernet.
10 M

5 (a) Briefly explain the three criteria's of a transparent bridge with example.
10 M
5 (b) Explain the following connecting devices: (i) Passive hub; (ii) Repeater; (iii) Bridge; (iv) Router; (v) Gateway.
10 M

6 (a) What is NAT? Explain how address translation is done in NAT.
9 M
6 (b) Why IPv4 to IPv6 transition is required? What are various techniques used in transition? Explain them.
8 M
6 (c) Bring out any 3 difference between IPv4 and IPv6 addressing schemes.
3 M

7 (a) Explain distance vector routing with an example.
10 M
7 (b) With a neat flow chart explain Dijkstra algorithm for the network shown in Fig Q7(b). Assume 'A' as root node. Mention the routing table for root. A refer Fig.Q7(b).

10 M

8 (a) How is TCP better than UDP? Explain services offered by TCP.
10 M
8 (b) What is Name Space? How is it classified? What is DNS?
10 M

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