Reg. No.
DEGREE EXAMINATION, 2008.
Eighth Semester
Computer Science and Engineering
EC 1008 HIGH SPEED NETWORKS
(Regulation 2004)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A- (10 x 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 t o 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. is based on the concept of soft state. Justify this statement.
PART B - (5 x 16 = 80 marks)
11.
Explain the B-ISDN reference model with a neat diagram.
Draw the format of a n ATM cell at UNI and NNI. Explain the
purpose of each field in the header.
Explain the protocol stack of IEEE 802.11 Wireless LAN with a
neat diagram.
Discuss about the different cabling and encoding schemes used in
the fast Ethernet.
12. (a)
Discuss the various reasons that lead to congestion in networks. (6)
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 a t the traffic
from the LAN to a WAN and hence to the outside world. Let us look
a t 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 packet length is exponentially
distributed Line speed from the router to the wide area is
9600 bps. The following question are asked.
What is the mean residence time for the router?
(2) How many packets are in the router, including those
waiting for transmission and the one currently being
transmitted for the percentile?
How many packets are in the router, including those waiting
for transmission and the one currently being transmitted for
the 95 percentile?
Describe the techniques followed in the network layer to deal with
congestion.
Consider a LAN with 100 personal computers and a server that
maintains a common database for a query application. The average
time for the server to respond to a query is 0.6 seconds, and 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.
What is the average response time ignoring line overhead?
(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) If 20% more utilization is experienced, will response time
increase by more or less than
13. Explain the mechanisms followed by the early TCP specification to
maintain the timer.
Explain the refinements proposed by Karn and
to improve the basic timer management mechanism
of TCP.
Explain the mechanisms followed by the early TCP specification to
manage the window.
(ii Explain the refinements proposed by Nagle and Clark to avoid the
silly window syndrome faced by the window management.
14. (a) Justify the need for Fair Queuing and explain the Weighted Fair
Queuing scheduling discipline.
(ii) Justify the need for the improvement in the basic drop tail
mechanism and explain the Random Early Drop dropping policy. (8)
Describe the various functional modules that must be present in a
router of the Integrated Services Architecture.
Discuss the limitations of the ISA framework.
15. (a) Discuss the labeling and label switched path of MPLS
Explain the stacking rules followed in the label switched path of
MPLS networks.
Or
Illustrate the different ways of placing the RTP in the
reference model.
Draw the RTP header and explain the various fields of RTP header
in detail.
