Advanced Network Technologies

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University of Sussex




DGM05
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SCHOOL OF ENGINEERING




MSc/PgD/Pg Cert Programme in Digital Electronics





LEVEL M



TERM ONE


2003
-
2004


Advanced Network Technologies






Examiner: Dr. E. Stipidis


Answer
FOUR

questions only

Time allowed:

3 hours


Open
-
note: maximum of 10 A4 sh
eets only.

Total number of questions = 6


All questions carry equal marks.


The figures in brackets indicate the relative weightings of parts of a question.



Special Requirements:

None










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1)

(a)

Describe the functionality of the following network devi
ces and highlight their differences:

(i)

Repeater

(ii)

Hub

(iii)

Logical Bridge

(iv)

Medium Access Control (MAC) Bridge

(v)

Router

(vi)

Gateway


Use as a reference the Open Systems Interconnect (ISO/OSI) layer reference model to
illustrate the functional layer for each of the above de
vices.

(12)


(b)

Define the functions of the internetworking devices [A, B, C, D] shown in Figure 1.1 below
and justify your answer.

(8)



Figure 1.1


(c)

If device B in Figure 1.1 were to be replaced with another internetwork
ing device so that
more CAN buses can be supported, what device would replace it and why?

(5)










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2)

(a)

Explain briefly the following:

(i)

How are ATM Cells routed through a network and how does this differ from
normal IP based networking.

(2)

(ii)

What is a Virtual Connection and how does this relate to Virtual Paths and
Virtual Channels?

(3)




(b)

With the aid of a diagram describe the relationship of Virtual Paths and Virtual
Channels as well as how these are used to switch ATM Cells between dif
ferent ports
on an ATM Switch.

(5)


(c)

The rest of the question is based on the network topology diagram illustrated in
Appendix.


Describe in a simple manner how a Virtual Connection is established to transfer
Video images between user A and user B and

how it is released.


Assume that the Video application is to be Connection Oriented and the shortest
route should be used.


Use the time diagram shown below the network diagram in the Appendix to illustrate
the communications flow and naming for each
of the Virtual Paths following the
existing Links names e.g. VP1 for Link1.

Explain briefly what happens if Link 2 fails.

Explain how Virtual Channels could be used on top of Virtual Paths.

(15)














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3)

(a)

With aid of a diagram explain the TCP/IP st
andard layer and relate that to the ISO/OSI
reference model.



What do UDP and TCP stand for? Differentiate between them giving examples that make
use of UDP or TCP services to support your answer.

(8)


(b)

How is a MAC address related to an IP address and
ARP?



Give a simple example of a MAC address and its related fields.

(5)



(c)

Give an example of a TCP/IP client
-
server application, where Host A is the Client and
Host B is the Server, explaining each step from the connection to the data transfer.

(12)






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4)

(a)

What do Connection Oriented, Acknowledged Connectionless and Connectionless
Services stand for? Give one example of an application for each of these services.

(6)


(b)

Explain briefly the following:

(i)

What is meant by the expressions, Flow Control and

Error Control?

(2)

(ii)

What is HDLC?


Your answer will focus only on the following: What does HDLC stand for?
Which layer of the ISO/OSI layer does it relate to? What is the
structure/topology of HDLC showing how different nodes communicate with
ea
ch other indicating if it uses distributed communication or Master/Slave based

communications?

(4)


(c)

Draw the traditional topologies for Ethernet and Token Ring Networks. Explain and
compare with the use of an approximation graph showing the Efficiency aga
inst Utilisation
of both Ethernet and Token Ring Networks.

(8)


(d)

A SME (small medium enterprise) company needs to install a new network in its premises
and the company has narrowed down the deployment to two network technologies in
terms of cost, Ethernet a
nd Token Ring. A final decision now needs to be made taking in
account the following requirements:

1.

High requirement of compressed Video distribution and processing through the
network.

2.


High requirement for all terminals to have a fair distribution of ne
twork resources to
serve the distributed multimedia system that they want to deploy on top of the
network.

3.

The SME wishes to utilise efficiently the network resources but it is not a high
priority.


You are required to propose a solution to the above requi
rements. Your answer will
include justifications for your proposal taking in account the application characteristics as
well as your proposed network technology characteristics.

(5)






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5)

(a)

What is ADSL? Explain with the help of a diagram how ADSL use
s the frequency
spectrum.

(5)



(b)

Define Classes A, B, and C for IPv4 networks. How many Class C networks can be
defined under a Class A network? What would be the standard NetMask for a Class B
Network?

(7)



(c)

In a Class C network that contains 8 s
ubnets there are 3 IP addresses causing problems in
the network. You need to create a subnet mask that can identify in which subnets the IP
addresses belong to as well as the Host numbers.





The IP addresses are:


193.230.8.57

192.225.18.66

225.18.191.1
88

(13)





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6)

(a)

What are the differences between Time Division Multiplexing and Statistical Multiplexing?
Use an example diagram with link Utilisation against Time to illustrate the differences.

(6)


(b)

List the methodologies used for ATM Traffic Control, b
riefly giving an explanation for each
one. Explain what is a Leaky Bucket Algorithm and how it is used.

(6)


(c)

What is meant by Congestion? Use a Router diagram to illustrate the concept. One of the
methods to deal with congestion is to use Choke Control
Packets. How are these used?

(6)


(d)

How does ATM provide Quality of Service (QoS) for multimedia applications?

How many service classes does ATM provide and how are they defined?

Give examples of different applications and how these can fit with the ATM Ada
ptation
Layer protocols.

What QoS parameters are used by ATM to provide the requirements for particular
application?

(7)


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Appendix

Attach to your answer script.

Student Registration number: ____ / ________________

Answer sheet for Question 2


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