UNIVERSITY EXAMINATIONS: 2017/2018
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE IN
INFORMATION COMMUNICATIONS TECHNOLOGY
BCT 3102 PERFORMANCE MODELLING OF COMMUNICATIONS
NETWORKS
FULL TIME/PART TIME/DISTANCE LEARNING
DATE: DECEMBER, 2017 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions.
QUESTION ONE
a. Describe the steps and process of performance management of networks
8
Marks
b. Explain the various tools used in performance management of networks
8Marks
c. Explain the Little’s Theorem 4 Marks
d. Examine the major applications of utilization metrics 6 Marks
e. Elaborate on any four network application performance factors 4 Marks
QUESTION TWO
a. Describe how the following concepts are used in network performance modelling
and analysis 15 Marks
i. The Sum Rule
ii. The Product Rule
iii. Bayes’ Rule
iv. Independence
v. Expectations
b. Discuss the applicability of queuing theory in network performance analysis
5Marks
QUESTION THREE
c. Discuss the various metrics that can be used to measure the performance of
networks 10 Marks
d. describe the properties of Poisson processes as used in performance modelling
and analysis 10 Marks
QUESTION FOUR
Propagation speed is speed at which a bit travels though the medium from source to destination.
Transmission speed is the speed at which all the bits in a message arrive at the destination.
(difference in arrival time of first and last bit). Latency = Propagation delay + Transmission
delay + Queueing time + Processing time
a. What is the propagation time if the distance between the two points is 12,000 km?
Assume the propagation speed to be 2.4 × 108 m/s in cable. 4 Marks
b. What are the propagation time and the transmission time for a 2.5-kbyte message (an
e-mail) if the bandwidth of the network is 1 Gbps? Assume that the distance between
the sender and the receiver is 12,000 km and that light travels at 2.4 × 108 m/s.
4Marks
c. What are the propagation time and the transmission time for a 2.5-kbyte message (an
e-mail) if the bandwidth of the network is 1 Gbps? Assume that the distance between
the sender and the receiver is 12,000 km and that light travels at 2.4 × 108 m/s.
4Marks
d. What are the propagation time and the transmission time for a 5-Mbyte message (an
image) if the bandwidth of the network is 1 Mbps? Assume that the distance between
the sender and the receiver is 12,000 km and that light travels at 2.4 × 108 m/s.
4Marks
e. A network with bandwidth of 10 Mbps can pass only an average of 12,000 frames per
minute with each frame carrying an average of 10,000 bits. What is the throughput of
this network? 4 Marks
QUESTION FIVE
Depending on the nature of the information communicated between the client and the server the
characteristics of the session can vary dramatically. An FTP session may involve a few packets
from the client to request a file followed by many packets from the server to send the file. A VoIP
session will involve large numbers of packets between two users and no obvious client/server
relationship. A hypertext transfer protocol (HTTP) session may involve long periods of inactivity
as the client reads the pages they have downloaded. Discuss the characteristics of a session that
may need to be considered in the design of the protocol and the network.
20 Marks
