EC 1008 - High Speed Networks ANNA UNIVERSITY QUESTION BANK

Computer Science and Engineering

EC 1008 - High Speed Networks

Part-A(10*2=20 marks)

1. Define cell switching.

2. Frame relay networks are faster than X.25 networks. Justify this
statement.

3. Mention any four queuing models used to measure the performance of
networks.

4. What is the purpose of choke packets in networks ?

5. Write short notes on slow start process of congestion control.

6. What is the necessity of a 3-way handshake protocol to establish a
transport layer connection ?

7. Mention any four features of ABR traffic.

8. What types of applications require GFR in ATM networks ?

9. What are the limitations of First Come First Served queuing discipline ?

10. RSVP is based on the concept of soft state. Justify this statement.


Part -B (5*16=80 marks)

11. (a) (i) Explain the B-ISDN reference model with a neat diagram. [8]

(ii)Draw the format of an ATM cell at UNI and NNI. Explain the
purpose of each field in the header.[8]

(OR)

(b) (i) Explain the protocol stack of IEEE 802.11 Wireless LAN with a
neat diagram.[8]

(ii)Discuss about the different cabling and encoding schemes used
in the fast Ethernet.[8]

12. (a) (i) Discuss the various reasons that lead to congestion in
networks.[6]

(ii)Consider a configuration in which packets are sent from computers
on a LAN to systems on other networks. All of these packets must
pass through a router that connects the LAN to a wide area
network and hence to the outside world. Let us look at the
traffic from the LAN to a WAN and hence to the outside world.
Let us look at the traffic from the LAN through the router.
Packets arrive with a mean arrival rate of 5 per second. The
average packet length is 144 octets and it is assumed that the
packet length is exponentially distributed Line speed from the
router to the wide area network is 9600 bps. The following
question are asked.

(1) What is the mean residence time for the router ?[2]

(2) How many packets are in the router, including those waiting
for transmission and the one currently being transmitted
for the 90th percentile ? [4]

(3) How many packets are in the router, including those waiting
for transmission and the one currently being transmitted
for the 95th percentile ? [4]


(OR)

(b) (i) Describe the techniques followed in the network layer to deal
with congestion. [8]

(ii)Consider a LAN with 100 personal computers and a server that
maintains a commmon database for a query application. The
average time for the server to respond to a query is 0.6 seconds.
The standard deviation is estimated to equal the mean. At peak
times, the query rate over the LAN reaches 20 queries per minute.
We would like to answer the following questions.

(1) What is the average response time ignoring line overhead ?[2]

(2) If a 1.5 second response time is considered the maximum
acceptable, what percent growth in message load can occur
before the maximum is reached ? [3]

(3) If 20% more utilization is experienced, will response time
increase by more or less than 20% ? [3]


13. (a) (i) Explain the mechanisms followed by the early TCP specification
to maintain the timer. [8]

(ii)Explain the refinements proposed by Karn Patridge and Jacobson/
Karel to improve the basic timer management mechanism of TCP. [8]

(OR)

(b) (i) Explain the mechanisms followed by the early TCP specification
to manage the window. [8]

(ii)Explain the refinements proposed by Nagle and Clark to avoid the
silly window syndrome faced by the window management. [8]

14. (a) (i) Justify the need for Fair Queuing and explain the Weighted Fair
Queuing scheduling discipline. [8]

(ii)Justify the need for the improvement in the basic drop tail
mechanism and explain the Random Early Drop dropping policy. [8]

(OR)

(b) (i) Describe the various functional modules that must be present in
a router of the Integrated Services Architecture. [10]

(ii)Discuss the limitations of the ISA framework. [6]

15. (a) (i) Discuss the labeling and label switched path of MPLS network.[8]

(ii)Explain the stacking rules followed in the label switched path
of MPLS network. [8]

(OR)

(b) (i) Illustrate the different ways of placing the RTP in the TCP/IP
reference model. [8]

(ii)Draw the TCP header and explain the various fields of RTP header
in detail. [8]

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