Case Study - After establishing a reputation in the Arts and Design Markets, the Singapore Arts Academy (SAA) considers expanding and investing into a new Multimedia department and courses by setting up campuses around Asia pacific region. - By Hansa Edirisinghe

1. DISTRIBUTED NETWORKING
BSc (Hons) Assignment
2011
DISTRIBUTED NETWORKING
Hansa K. Edirisinghe
BSc (Hons) University of Portsmouth, UK
3/1/2011

2. Case Study
After establishing a reputation in the Arts and Design Markets, the Singapore Arts Academy
(SAA) considers expanding and investing into a new Multimedia department and courses by
setting up campuses around Asia pacific region.
Currently, the Academy has a very poor data communication network. As you have designed
most of the other institutions’ network infrastructure, the dean of the Academy contracted you to
design a sound network that will cope with the current and the future demands.
Some facts about the current network at the Academy:
The school is located on the two-storey of the converted shopping mall in the City State of
Singapore. Each floor has several departments. Each department has 10 to 15 members of staff.
The ground floor comprehends the administration and the account departments. For payment,
the administration and the account departments are considering the use of smart cards based on
Biometrics technologies and Radio Frequency Identification (RFID). The Academy has a
corporate minicomputer (a UNIX computer) that processes all accounting data, and a Microsoft
File Server for students support.
The first floor accommodates a team of 30 academics, three IBM compatible labs, and two
multimedia labs. The two-multimedia labs are to be equipped with the latest multimedia tools
and technology. Each lab contains 20 personal computers, including wireless access points. The
applications running on two servers include Lotus Notes, remote access, student/staff workbench
and a management information system (MIS). Twenty of the existing classrooms in the school
are not connected to the network. The faculty, staff and students require communication with
each other via electronic mail, and have access to the Internet.
As the Academy expands, the network connections were put in as required. There has been some
discussion about establishing a corporate website as well. The dean is interested in running a
collaboration application like groupware, Voice over IP (VoIP) and Video Conferencing with
University partners in Boston, USA, and London, UK.
The current infrastructure runs on a token ring network with a capacity of 4Mbps. Furthermore,
the communication between various departments, connected to the network and the University
partners, is established via emails and Internet services.
Requirements of the proposed network for the Academy:
1) To implement a LAN and WLAN for the Academy which replace the current 4Mbps token
ring network,

3. 2) To implement access points for wireless access for the students, staff and guests,
3) To link up all the office networks together on to a backbone network to support higher
volume of data,
4) To Identify and evaluate the state-of-art smart card Biometrics Technologies, and the Radio
Frequency Identification (RFID) mechanisms for payment,
5) To include further network expansion at the Academy to tolerate additional increases in the
network traffic such as the immediate inclusion of 20 computers, and to set up a web server
in order to establish a corporate website,
6) To implement a WAN to automate the data transfer between all the offices and the
University partners’ networks,
7) To provide a high bandwidth platform for collaboration application like groupware, Voice
over IP (VoIP) and Video Conferencing with the University partners and other campuses,
8) To identify and resolve key issues relating to network security for the school.
THERE ARE FIVE MARKS OVERALL ALLOCATED, FOR USE OF LANGUAGE
AND PRESENTATION
QUESTION 1
Discuss suitable LAN and WLAN technologies for the Academy. Critically evaluate your
proposed solution in terms of protocols, topology and cabling used. A details description of the
protocol, the advantages and pitfalls of the topology and a technical specification of the cables is
mandatory.
QUESTION 2
Critically discuss how to minimize the network congestion and the data access between
Academy campuses and the University partners’ networks using WAN connectivity. Your
discussions should include two different possible types of networks to connect between the two
continents. Your answer should also include the protocols associated, data rate, cost, and
performance aspect.
QUESTION 3
Prepare a comprehensive contingency plan for the Academy network in terms of strategy and
appropriate hardware/software solutions to ensure network availability. You should include four
significant threats that would affect network availability in case of major service disruptions and
propose counter measure mechanisms.

4. QUESTION 4
Critically evaluate three key strategic network security safeguards that can help to secure the
Academy Network. You should provide a detailed description of how these security mechanisms
can be used to secure the network and a comprehensive assessment of the advantages and
disadvantages of your proposal.
QUESTION 5
Design and explain, with the aid of a suitable fully labelled network diagram, how far the
proposed Academy Network meets the requirements listed. Provide a detailed assessment to
justify your proposed network, and any recommendations that you made for the specific
hardware and software technologies. You must clearly stated their usage in your proposal.

5. Table of content
Question 1................................................................................................................................... 2
Question 2................................................................................................................................... 8
Question 3................................................................................................................................... 12
Question 4................................................................................................................................... 15
Question 5................................................................................................................................... 17
List of reference.......................................................................................................................... 19
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6. 1. Question 1
Considering the current network of Singapore Arts Academy, We have to improve several arias
when establishing a strong data communication network within the branch campuses and among
the campuses.





Topologies which are going to use
Hardware the build the network
Reliability, effectiveness and cost
Contingency Plane
Network system Software
Token Ring is the currently using Technology which connects all the computers to ring or stare
and use a token passing methodology to transfer data or communicated between two computers.
When one computer needs to transfer data, it receives a free token, discard it and replace new
token with its own data, address to IP and release to the network. When the addressed IP
received data, it makes as received and passes it back to originating station, discard data frame
and release new token to the network. Token Ring data transfer rate is 4Mbps or 16Mbps. This is
a quite old technology and its devices are much more expensive. The main disadvantage of token
ring is only two stations in the network can send and receive data at one time.
Choose a LAN and WLAN technology
Considering about the requirement, I would like to propose 4Mbps Token Ring connection
replace with the Ethernet with the bandwidth of 1000Mbps as the Local Area Network of the
Academy. Ethernet use the Carrier Sense, Multiple Access / Collision Detect (CSMA/CD)
protocol to data communication.
CSMA/CD
Carrier Sense: Every nod is listening to the Ethernet wire
and check whether any device transmitting data. If
transaction happens, the nod waits while the current
transaction gets finish.
Multiple Access: It is possible to sensing (listening and
waiting to transmit) data from one or more devices at the
same time.
Collision Detection: If more than one ethane nods transmit
data the same time, Ethernet is able to detect collision.
Figure 1.1 CSMA/CD
Advantages of the Ethernet
Source : http://www.payer.de/cmc/cmc0801.gif
 An any network nod can send data in any time
 Bandwidth availability 10, 100, 1000Mbps
 Much easy to plane and low installation cost
 Network components such as cables, Network interface cards and Connectors as low in
cost
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7. 



Ethernet can work with Star topology, as well as Bus topology
Trustworthy and reliable when working with home and office network environments
It is easy to add and remove computers on the network
Supported by most Software and hardware systems
Disadvantages of Ethernet
 A large traffic rate such as 40% - 50% may delay the whole network
 Packet swishing produces visible delay
Which protocols to select
A protocol is the special set of rules that end points in a telecommunication connection use when
they communicate. (SearchNetworking.com 2011)
OSI and TCP/IP are the two models which
gather network protocols in to layers.
TCP/IP is an open source protocol which uses
to any kind of network, but there are some
restrictions also in the TCP/IP. In the SAA
network there are lot of changes can happen in
that protocol. So in side this protocol there is
advantages and disadvantages in the protocol
which use this university network. There are
IBM main frames compares also in this
Academy building. But the TCP/IP protocol is
unable to use in the IBM servers. So it will be
a pitfall in the university network in
Singapore. However as its mention the Art and
Design University the TCP/IP is a very reliable
protocol because less cost effect and it’s easy
to implement the network in any second.
Because the there are selected web sites or host or IPs has to block in the university. TCP/IP can
make change the routing configuration easy and make block the site and access the sites the user
need and wants. This makes advantage of the TCP/IP.
Selection of a Network Topology
Topology is a layout which devices can interact with each other. There are four major types of
topologies and there are plus points, as well as minuses in each and every topology. According to
them we should select the best suitable topology for our environment.
Topology
Bus
Advantages
Easy to control.
Easy to implement.
Most suitable for small networks
with 10 – 15 nods.
Disadvantages
Cable length limited.
Number of stations limited.
Cannot perform well.
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8. Ring
Star
Mesh
Transition data packets among two
nodes pass through the all other
nodes in the network.
Central server not required for
configuration.
Simplicity of operation.
Add and remove nod is easy.
Failure of one node will not affect
to the whole network.
Error detection is easy.
No network traffic occurs.
Modification of a cable or nod does
not affect to the entire network.
Failure of single device or cable will down
the entire network.
Add and remove nod is difficult.
Failure central device fails the entire
network.
High cost.
Considering of SAA environment, I would like to suggest Star Topology.
Star topology connects all the devices in the view of a
visual star. There is a central HUB or Switch. All the
other Nods (Computers, servers, printers, fax
machines, clock Machines) connected to the Central
Device. This central HUB or Switch acts as a repeater
for the data flow. The total data communication
network handles by the central device. Each and every
bit of data drives through the central device to its
destination nod. So a failure of one cable or failure of
one nod does not harm to the entire network. But
failures of the central device (it can be HUB or a
Switch) come out with an error the entire network
goes down. The nature (layout) of star network makes
really easy of trouble shooting within the network.
For the configuration of star, it is possible to use twisted
pair (STP or UTP) cables or Fiber-optic Cables.
Widely using cable type for Star is UTP cables
(Unshielded Twisted Pair cables) and the network port that is connected to both ends are RJ45
ports.
Looking at the Singapore Art Academy’s environment, it’s a two storied building. It’s facilitated
with 3 IBM and 2 Multimedia labs with two departments for Staff. Two departments and the File
servers are in ground floor.
Scenario:
An IBM lab equipped with 20 IBM PCs per each lab and Multimedia labs with 20 PCs.
According to the standard switch sizes, we have to use 24 port switches and connect the entire
lab PCs directly to switch as per the star topology layout. It was connected by UTP cables
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9. Hierarchical Star
The hierarchical topology is used to make
more connection ports available within an
building, office, university or Institute.
Plugging outlying switches (access switches)
into a master switch (Distribution or Core
switch) gives more hosts a place to plug in
without having to pull additional cable into
the area.
Advantages of Star







Star topology has simply
understandable layout
It makes easy to install the topology
Figure 1.4 Hierarchical Star
Source : http://tjliu.myweb.hinet.net/COA_CH_12.htm
Star performance is good. The way of
star transaction process, it performs
better than other network topologies.
When there is a communication goes on, just only tree network devices and two network
links actively participate to the communication process from the entire star. It can avoid
the unnecessary traffic within the network.
The rate of Error detection in star network devices, higher than other networks, because
of the simplicity of network structure.
If a failure occur in one nod does not harm the entire network connection and it is easy to
repair or replace the defected nod without breaking the entire network.
According to star structure, it is very easy to adding new devices and grove the network.
Disadvantages of Star



The entire network is highly depending on the central hub. If the hub (Switch) comes up
with error, the functionality of entire network goes down.
There are limited in the central hub. So there is a limit to grove the network and
connection of one new nod to star effect entire performance cycle of the network.
The performance level is dropped, when switch hands its high traffic, then the entire
network will get slow.
Network Cables
Within a wired network, cables play one of the main roles on the network.
 Twisted-pair (Shielded and Unshielded twisted are the two categories of Twisted pair)
cables
 Coaxial cable (very famously used before twisted pair)
 Fiber-optic cables are the generally using network cable types. By looking at the cost of
cables, data transfer speed, usability and durability, we need to identify, what is the most
suitable cable type for our network.
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10. Twisted-pair cables
Two insulated copper wires warped around each other are Twisted-pair. When the electric
signals walking through the copper wire, it generate a small magnetic field around the wire
(according to Fleming’s right-hand thumb rule). The twisted nature of twisted pair cables is
minimize this disturbance. Ethernet over twisted-pair is not new within a building amount
several floors and several partitions.
Two typed of twisted-pair cables are;

Unshielded twisted pair (UTP)

Shielded twisted pair. (STP)
Unshielded twisted-pair (UTP)
UTP cable composed with eight copper wires which are covered by material which reduce
electromagnetic interferences. It reduces its electromagnetic interference according to the way it
twisted. UTP is low in cost and it is possible to use major networking architectures. Cable is very
flexible and easy to install. I suggest UTP cabling is the most suitably to an environment like
SAA. UTP cable can transfer from 10 Mbps to 1000Mbps in speed and the maximum cable
length for gigabit is Ethernet is 100 meters. Connecter would be RJ 45 and the cost is low. So
UTP is the most suitable cable type for SAA network. Because we have more than 120
computers and servers to connect with WAN and we selected 1000Mbps (gigabit) Ethernet to
implement the new network.
Shielded twisted-pair (STP)
STP has four pairs of copper wires and each pair is wrapped with a metallic foil, then these four
pairs again wrapped with a metallic foil. This is why we call it as Shielded and this reduces the
outer electromagnetic interferences and the inner electronic disturbances as well. Comparing
with the UTP cable STP prevents inner and outer disturbances better than UTP. But STP is
expensive and installation is difficult. Considering the SAA environment, it is not good enough
to go for STP cabling network according to the academy’s requirement and the STP cabling cost
probably be and additional cost to the academy.
Selection Cables for the topology
When we selecting a cable, we should the always look into bellow characteristics of a cable. The
characteristics which are
 Maximum segmentation Length (max length of the cable that can transfer data)
 Speed (speed in bits per second)
 Cost (cheap or expensive)
 Advantages and disadvantages of the using the selected cable type of cable.
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11. As above mentioned, my suggestion is UTP cable the most suitable cable for SAA networks out
of the other 4 cable types, according to requirements.
UTP Cable Standards
UTP cables divide into categories according to UTP standards. They are Cat 3 UTP, Cat 5 UTP,
Cat 5e UTP, Cat 6 UTP Cat 6A UTP and Cat 7 UTP. But we have to forget about the Cat 3 UTP
and Cat 5 UTP, because those can carry data only up to 10Mbps and 100Mbpd Ethernet.
Cat 6A UTP and Cat 7 UTP are designed for 10 Gbps Ethernet. So we are not necessary to go to
that much unwanted expense. Cat 5e UTP and Cat 6 UTP is only suite for Gigabit Ethernet.
Thus Cat 5e UTP can handle Gigabit Ethernet; I select Cat 6 UTP to configure the Academy
network.
Cat 6 UTP has backward compatibility. It support to the occurring rate of Crosstalk and noise
damage to the signal, keep on low level. Provide performance frequency up to 250MHz. Cat 6
UTP 10BASE-T UTP, 100BASE-TX (Fast Ethernet) UTP, 1000BASE-T/1000BASE-TX
(Gigabit Ethernet) UTP. Proper integrated Cat 6 UTP cables supports up to 10Gbps speed.
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12. 2. Question 2
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13. Network Congestion
When a nod or device transmits more data at ones and overload, network congestion takes place.
This congestion reduces the accuracy and trustworthiness of network and communication data.
Because it delay the communication speed and the congestion might loess or block data packets.
When the switching nod getting congested and the round trip time duration increases, the
network problems are not addressable.
Going through the SAA network, we can find several points which can occur network
congestion.
When multiple links feed its data into to single link. It usually happen the points which internal
LANs are connected to WAN, such as the academy internal network links University partners in
Boston and London.
According to the proposed network, the academy network usage is very high. Other than the
current use wireless router implementation Smart card Biometrics Technology, RFID, newly
including computers, web server, VoIP Video Conferencing and new security futures require
more bandwidth and speed. So the routers in core network are capable to handle a large traffic.
Otherwise it will be another reason for occurring congestion.
Mainly the academy internal and external communication purposes and data and file transaction
purposes with partner Universities, TCP/IP such as Internet is essential. But it is a major point
which occurs of terrible network congestion, because the basic connection is less nature.
Minimise the network Congestion
We can use several telecommunication technologies to minimise congestions and sometimes it
makes fast data transmission. These telecommunication services designed for connect LAN and
WAN connectivity. As we discussed earlier, network congestion directly related theses services.
Frame Relay, X.25 and Asynchronous Transfer Mode (ATM) are some of them.
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14. Frame Relay
Frame relay is a digital dedicated low cost data transmission service, which has higher data rate
intermittent traffic between Local area networks (LAN to LAN), between end points in Wide
area networks (WAN), remote accesses and access to internet. The information divided into data
packet, labelled with an ID and carries to the identified destination with very efficient way. This
process is known as packet switching technology. It sends data frames (data packets) over the
network for communication and checking errors while the transmission process. When there is
any error detection it retransmits the data.
In SAA network we can use Frame relay with the transition from Router. It makes our data
transaction fast and efficient.
This network service transmits data between remote networks with leased line access. Frame
relay has 56Kbps to 45Mbps range of bandwidth and it is possible to select the bandwidth which
is suit to our Academy usage. The physical connection to our frame relay circuit is known as port
speed.
Packet switching technology is also use with TCP/IP and X.25.
Frame Relay Structure
Figure 2.1 Frame Relay Structure
Source : http://www.protocols.com/pbook/frame.htm
Protocol use in Frame Relay
The protocol which is using with frame relay is HDLC. HDLC stands for High-level Data Link
Control. HDLC is the protocol which manages the flow of data in Frame Relay. This is the most
common protocol using in layer 2 in OSI model.
ATM
Asynchronous Transfer Mode is a technology based on transfer data in cells or packets for a
fixed size. A cell which is used with ATM is small in size and it allows transmitting video, audio
and computer data along network.
So it is possible to use ATM to our technology between switches and end user computers of
multimedia Labs.
ATM creates a fixed cannel among two points when the beginning of the transmission process.
ATM utilized for high bandwidths like 34Mbps to upwards.
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15. X.25
X.25 is the advances version of Frame Relay. X.25 divides into three categories. Those are data
DTE, DCE and PSE. DTE stands for terminal equipment, DCT stands for data circuitterminating equipment and PSE stands for packet-switching exchange. DTE devices are
endpoints such as PCs, terminators, printers, scanners that communicate across X.25 networks.
DCE devices are communication devisers such as modems and packet switches. DCE are the
interface between DTE and PSE. PSE are swatches to compose bulk carriers of network.
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16. Figure 2.2 Characteristics between Frame relay and X.25
Source : http://www.dcbnet.com/notes/framerly.html
3. Question 3
According to the structure of the Academy and considering about the new requirements there are
several hardware devices to configure a better network and software to control the network and
track the transaction. We have to consider about the several facts including reliability, efficiency
and cost.
Hardware
Switch
Switch is used to interconnect several
hosts(nods) together. There are switches in
different sizes. The common sizes are 4
port, 8 port, 16port, 24 ports and 48 port
switches and the size of the switch can be
selected according to the according to our
network. For each port there is a light
which blinks when it connected to
network. Switch operates at the data link
layer, which is the second layer of the OSI
model.
Figure 3.1 Switch
Source :
http://lh4.ggpht.com/_9R2czlR5ELs/SoDac_wAD1I/AAAAAAAAA
Qs/5rl4f0gu5lc/img-xavb1004-back.jpg
The MAC addresses of all the devices
which connect to switch are in its storage.
When a data frame passes through the switch, it examines the destination MAC address.
According to the Destination device MAC and the data frame’s destination MAC, switch decides
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17. to which port, the data frame to copy. If the data frame’s destination MAC is unknown, then
switch will broadcast the frame to all of its ports.
We have 5 computer labs and two departments at the ground floor. There are several serves to
connect to the network. Because of that, this device is important to us. Make star network within
the IBM and Multimedia labs, connect servers including file, application and web, to the
Academy’s LAN. Switch can support 10/100/1000 Mbps port transfer rate and multiple switches
in the same network can support for different speeds. The price of a switch differs from brand to
brand, sizes and transfer rates. However a 24 port switch which supports for 1Gbps speed, we
need to allocate $100 - $150 from our SAA networking budget.
Wired Router and Wireless Router
Router is a device which transfer data to nods and work as a filter of data and its task is to copy
frames from one to another. It is a device which uses to connect on internet and other outside
networks. Router configuration allows you to apply filters, block accesses and deny access to
selected hosts. According to OSI model router operates at the network which is layer number
three.
Router use one more than one routing protocols
to create its routing table and looking at the
routing table router makes its decisions. Wired
routes are accessible with interface types, such
as DSL, Ethernet, Fast Ethernet, Fiber
Distributed Data Interface (FDDI) and Token
ring.
In the SAA network we need a wired router
and as well as wireless router. The academy’s
IBM and Multimedia labs have computers with
wireless access points and they require
implementing access points for wireless access for
Figure 3.2 Wireless Router
Source : http://kb.netgear.com/app/answers/detail/a_id/1000/~/whatthe students, staff and guests.
is-a-router%3F
Wireless routers are available with interfaces such
as IEEE 802.11(Wi-Fi)
How router works
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18. Threats affect to the network availability
Flood, Earthquakes, Tsunami
These are natural threats which we cannot stop or get rid of it. But we can minimise the damage
from these threats. For an example we have out academy database server and the backup server
in the same building. But will destroy all our property when sudden Tsunami disaster. If we keep
another backup server in our branch campuses in another country, it will minimise the damage
us.
Fire
Using fire alarm system and CO2 fire extinguishers will minimise the damage.
Sudden power failures
Sudden power failures can affect to computer software, hardware and network devices. UPS is a
device which supplies power from its battery for about 5 - 10 minutes, until power supply
connected to generators. Otherwise these UPS power supply time is enough to turn of the
devices.
Trojan horse, Viruses, Worm
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19. These are small software which designed to delete or corrupt data in the computers, databases
and servers. This makes the PCs and servers to slow, and sometimes it harms to the network.
Using a fire wall and properly updated antivirus software can avoid these Virus infections.
Hackers and Unauthorized Access
People can come to our academy network without permission and harm or seal machined data
and network data. Not only the data, they can seal our hardware items as well. Using a password
protection to every PC is the primary protection for the network. Using different passwords even
from lab to lab is better for the security. Keep network administration passwords and server
passwords confidentially is essential. When the students, parents or staffs logging in to the
system there should be audit log. Audit log means there will be records of logins and the record
of the activities.
4. Question 4
It is essential to maintain a very good security system for large network like academy network,
which spread worldwide. There are a lot of ways which can attack the network.
Attack Sophistication vs. Intruder Technical Knowledge
Figure 4.1 Attack Sophistication vs. Intruder Technical Knowledge
Source : www.andrew.cmu.edu/course/95-752/notes/netsec.ppt
Firewall
Firewall is a secure machine, which is works between a private network and a public network.
Normally firewall closely working with a router program, and check each and every network
packet to determine whether to forward it toward its destination.
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20. How Firewall Works…
There are lots of firewall screening methods. A Simple one is to screen requests to make sure
they come from acceptable domain name and Internet protocol address. Firewall use one of these
methods to control the traffic flowing in and out of the network.
Packet Filtering
Proxy service.
Shameful inspection
Biometrics authentication Techniques
Biometric authentication used to identify the person’s physical, biological characteristics
uniquely. This can be used in ongoing and absolute identification.
Eg: finger prints, Foot prints, Walking Style, DNA patterns, Voice
VPN
VPN is a private network which is used to
communicate with remote sites.
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21. 5. Question 5
Branch campuses network
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22. Full network, main campus network and branch
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23. Reference
SearchNetworking.com (2011) accessed 4 March 2011
http://searchnetworking.techtarget.com/definition/protocol
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http://en.wikipedia.org/wiki/Network_topology
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http://www.exforsys.com/tutorials/networking/star-topology.html
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http://www.linktionary.com/c/congestion.html
TCP Congestion Control Available at jpkc.ncwu.edu.cn (2011) accessed 27 Feb 2011
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http://www.shopforbandwidth.com/frame-relay.php
X.25 Available at networking.ringofsaturn.com (2011) accessed 2 March 2011
http://networking.ringofsaturn.com/Protocols/x25.php
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