Reg. No. :

M.E/ M.Tech. DEGREE EXAMINATION, JANUARY 2011.

First Semester

Computer Science Engineering

(Common to Software Engineering and Information Technology)

241103 — COMPUTER NETWORKS AND MANAGEMENT

(Regulation 2010)

Time : Three hours Maximum : 100 marks

Answer ALL questions.

PART A — (10 × 2 = 20 marks)

1. What is cut-through switch? How is it different from store-and-forward switch?

2. Which protocol provides data link control for X.25? How does it assure

reliability in transmission?

3. There is congestion in the ATM network. How is it indicated?

4. List the parameters associated with queuing model

5. Compare credit based and rate based explicit congestion signaling approach.

6. What are per-hop behaviors (PHB)? How does an individual router

discriminates packet based on PHB?

7. Draw the block diagram of DS traffic conditioner.

8. What are the parameters defining a session in RTP?

9. List the categories of services defined by ISA.

10. How is QoS provided for a time application and how is it achieved specific to

audio?

Question Paper Code : 20074

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PART B — (5 × 16 = 80 marks)

11. (a) (i) Suppose a receiver in ATM network is in detection mode. A sender

sends a block of user data which gets corrupted on the way to

receiver

• What happens to the receiving end if a single or multi bit

error occurs in the payload of the cell transmission?

• How does the receiver reacts if the above error occurs in the

header and it is in correction mode. (8)

(ii) Explain the IEEE protocol architecture for Wireless LAN. (8)

Or

(b) (i) Consider a bus LAN with a number of equally spaced stations with

a data rate of 10 Mbps and a bus length of 1 km.

• What is the mean time to send a frame of 1000 bits to another

station, measured from the beginning of transmission to the

end of reception? Assume a propagation speed of 200m/ sµ .

• If two station begin to transmit at exactly the same time,

their packets will interfere with each other. If each

transmitting station monitors the bus during transmission,

how long does it need to wait before it notices interference?

(8)

(ii) Explain the different service categories in ATM network. Justify

aptly which among these services come under best effort and

guaranteed service classification of the Internet. (8)

12. (a) (i) The owner of a shop observes that on average 28 customers per

hour arrive and there are typically 10 customers in the shop. What

is the average length of time each customer spends in the shop? (5)

(ii) Differentiate single server with multi server queue. (5)

(iii) Explain the different frame relay congestion control techniques.

What is committed information rate? How does it provide fairness?

(6)

Or

(b) (i) At an ATM machine in a supermarket, the average length of a

transaction is 4 minutes, and on average, customer arrive to use the

machine once every 7 minutes. How long is the average time that a

person might spend waiting and using the machine? What is the

90th percentile of the residence time? On a average how many

persons are waiting to use the machine? (8)

(ii) Explain the interaction of Queues in Data network. What are the

key issues related to congestion in such network? (8)

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13. (a) (i) Define the three way handshake of the TCP initialization protocol

in detail using time outs. Explain how it avoids misunderstandings

caused by a delayed packet. (8)

(ii) Explain sustainable cell rate algorithm? How does it differ from

peak cell rate algorithm? (8)

Or

(b) (i) Suggest possible improvements that can be given to TCP, based on

the suggestion propose a TCP window flow control scheme that

varies the window size in accordance to the congestion. Propose a

simple mathematical model that can be used to analyze the

performance of your scheme. (8)

(ii) What are resource management cells? Explain a ABR RM cell

format. (8)

14. (a) (i) Compare elastic and inelastic traffic. (4)

(ii) Explain the Integrated Service Architecture implemented in router.

(8)

(iii) A single video source transmits 30 frames per second, each

containing 2M bits of data. The data experiences a delay jitter of 1s.

What size of delay buffer is required at the destination to eliminate

jitter? (4)

Or

(b) (i) Describe the key element of controlled load service. (6)

(ii) In fig 1, flow A,B,C,D are processed at one of the output of a routes.

For each packet, the time it arrives its label are indicated in the

fig 1. Specify the order of packet transmission, using weighted fair

queuing scheduler. The scheduler scans the flows, starting from A.

Assume flows A,B,C.D all given a weightage of 1,2,1 and

2 respectively of the output capacity. (10)

Fig. 1

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15. (a) (i) Explain the different packet formats in RTCP? (10)

(ii) Explain how packets are forwarded in multi protocol label

switching. (6)

Or

(b) (i) What is receiver initiated reservation? Explain soft state

reservation with a neat diagram. (8)

(ii) Explain the different reservation styles in RSVP. (8)

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