Code No: 36043

R05

Set No. 2

1. (a) Explain in detail binary count down collision free protocol?

[8+8]

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(b) Give the detailed description of 802.3 frame format?

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III B.Tech II Semester Supplimentary Examinations,January 2010 COMPUTER NETWORKS Common to Electronics And Computer Engineering, Electronics And Control Engineering, Computer Science And Systems Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????

2. (a) Explain one -bit sliding window protocol. Give the advantages and disadvantages of one-bit sliding window protocol?

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(b) Discuss the services provided by the data link layer to the network layer? [8+8] 3. Give the format of TCP segment Header and explain its different fields.

[16]

4. (a) What is e-mail? How e-mail is different from ordinary file? (b) What is the role played by user agent in E-mail system?

[6+10]

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5. (a) Compare Circuit switching with Packet switching.

(b) Consider any two networks of your choice which support Circuit switching or Packet switching and explain them in detail. (c) Explain the strategy that can be used at the receiver to achieve reordering of the packets. [6+6+4] 6. (a) Differentiate between the following:

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i. Category 3 twisted pairs & Category 5 twisted pairs ii. Broad band networking using dual cable & single cable iii. Single mode fiber and multi mode fiber

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(b) Which is more efficient, circuit switching or packet switching? Why? In a two byte address field, what is the maximum number of permanent virtual circuits possible? What about a three byte address? [9+7]

7. (a) With a neat diagram explain the relation between layers at an interface? (b) Define OSI reference model. Suppose in an arbitrary network as shown in Figure 7b the Host1 communicates with Host2. During the process of communication which layers as per OSI reference model will remain transparent to the nodes A to D and why? [8+8]

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R05

Set No. 2

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Code No: 36043

Figure 7b 8. (a) How congestion is controlled in ATM?

[8+8]

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(b) Explain ATM LAN emulation.

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Code No: 36043

R05

Set No. 4

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III B.Tech II Semester Supplimentary Examinations,January 2010 COMPUTER NETWORKS Common to Electronics And Computer Engineering, Electronics And Control Engineering, Computer Science And Systems Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Write short notes on:

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(a) Ethernet (b) Wireless LAN (c) Source routing bridge (d) Remote bridges.

[4×4=16]

2. (a) Discuss in detail about Time division switches?

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(b) With a neat diagram explain ISDN system with a PBX for use in large businesses? [8+8] 3. (a) What are the different flags in TCP segment? Explain each of them.

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(b) How TCP uses sliding window to achieve flow control?

[10+6]

4. (a) An alternate to a LAN is simply a big timesharing system with terminals for all the users. Give two advantages of a client-server system using a LAN. (b) What are the differences between TCP and UDP? (c) Discuss about Novell NetWare architecture?

[4+4+8]

5. (a) One way of detecting errors is to transmit data as a block of n rows of k bits per row and adding parity bits to each row and each column. Will this scheme detect all single errors? Double errors? Triple errors?

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(b) Differentiate between sliding window protocol using go-back-N and sliding window protocol using selective repeat. [8+8]

6. (a) What are ATM Service categories? Explain. [8+8]

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(b) What is Quality of Service? How ATM supports Quality of Service?

7. What is Authentication? How it is different from Authorization? Explain in brief different Authentication protocols with their relative merits and demerits. [16] 8. (a) Is hierarchical routing a separate routing algorithm or just a strategy for reducing the complexity of routing. (b) When do use hierarchical routing. How it reduces the exponential growth of routing tables. Illustrate with an example. [6+10] ????? 3

Code No: 36043

R05

Set No. 1

1. (a) Explain the techniques for controlling packet life time.

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III B.Tech II Semester Supplimentary Examinations,January 2010 COMPUTER NETWORKS Common to Electronics And Computer Engineering, Electronics And Control Engineering, Computer Science And Systems Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????

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(b) What is forbidden region? Explain how sequences numbers are given to TPDUS. [8+8] 2. (a) What are the two common goals of ATM switches? Explain about input queuing at an ATM switch?

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(b) Differentiate between synchronous and asynchronous transmission?

[8+8]

3. (a) Discuss about the file key assumptions in case of dynamic channel allocation in LANs and WANs? (b) Discuss in detail the working of token bus?

[8+8]

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4. (a) With the help of diagram explain the encryption model.

(b) What is the role of key secrecy and algorithm secrecy in security? (c) What are the approaches for cryptanalysis?

[8+4+4]

5. Define Adaptive and Non-Adaptive routing. Classify the routing algorithms in to adaptive and non adaptive type with suitable justifications. [16] 6. (a) Explain Load shedding for congestion control.

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(b) What is Jitter? Why it is important to control jitter for Audio and Video applications? How Jitter is controlled? [6+10]

7. (a) Compare point -to-point channels with broadcast channels along with suitable examples?

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(b) A collection of five routers is to be collected in a point-to-point subnet. Between each pair of routers, the designers may put a high speed line, a mediumspeed line, a low-speed line, or no line. If it takes 100ms of computer time to generate and inspect each topology, how long will it take to inspect all of them to find the one that best matches the expected load? [8+8]

8. (a) Consider an error-free 64 kbps satellite channel used to send 512 byte data frames in one direction, with very short acknowledgements coming back the other way. What is the maximum throughput for window sizes 1,7,15 and 127?

4

Code No: 36043

R05

Set No. 1

(b) What is pipelining? What are its advantages? What are the issues that raises when pipelining frames over an unreliable communication channel? Mention the approaches to deal with these errors? [8+8]

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Code No: 36043

R05

Set No. 3

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III B.Tech II Semester Supplimentary Examinations,January 2010 COMPUTER NETWORKS Common to Electronics And Computer Engineering, Electronics And Control Engineering, Computer Science And Systems Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Discuss about fast Ethernet cabling?

[8+8]

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(b) Explain various token bus control frames?

2. Explain in detail the two data link protocols widely used in the Internet? 3. (a) Writ short notes on the following: Unshielded twisted pair (UTP) Base band coaxial cable Broad band coaxil cable Optical fiber

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i. ii. iii. iv.

[16]

(b) What is the band width of a noiseless channel that can transmit binary signals at a rate of 6000bps? [12+4]

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4. (a) Compare a conventional TDM leased line with an ATM PVC from the user’s point of view and from the network operator’s point of view. Which feature of PVC makes it attractive from both points of view. (b) Explain how ATM fixed size cells makes cell switching quicker. (c) What are the applications which use constant bit rate and variable bit rate services of ATM? [5+5+6] 5. (a) What is one time pad? What are its merits and demerits?

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(b) What is the role of redundancy in encryption?

[6+10]

6. (a) What is the format of Cell in ATM? (b) Compare Permanent V.C. with Switched V.C. in ATM.

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(c) How fixed size cells increases the speed of switching?

[6+5+5]

7. What are the limitations of using Distance vector routing in mobile networks. Suggest ways of adapting Distance vector routing to mobile networks. [16] 8. (a) What are the distinct characteristics of local area networks, explain briefly? Why is a LAN required and what objectives are achieved by having a LAN (b) A group of 2n − 1 routers are interconnected in a centralized binary tree, with a router at each tree node. Router i communicate with router j by sending a message to the root of the tree. The root then sends the message back down to j. Derive an approximate expression for the mean number of hops per message for large n, assuming that all router pairs are equally likely. [8+8] 6

Code No: 36043

R05

Set No. 3

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