The ITGS Wiki at BHS - Recently Updated Pages

People and Machines

jennnny(: — Sat, 07 Nov 2009 11:54:49 CST

The interaction of humans with IT hardware raises all the issues encountered in this section, as well as additional ones such as the following.

Who controls the design of technology and the pace of its introduction?
How safe and effective is the design?
Is technology going to extend human faculties and make work easier and more pleasant, or are machines going to displace humans and lead to mass unemployment?
Is technology used appropriately, or should a better, possibly non-technological alternative be found?
Which areas of human endeavour are best served by IT systems?
Which social and ethical issues arise from a comparison of people
and machines in the following areas: stamina, memory, accuracy, speed, analysis, synthesis, judgement, innovation, creativity?

In The News

Not Tonight, Dear, I Have to Reboot

This article explains how over the years scientists, inventors, and other technology people have to invent things such as robots to show how robots have come to be quite useful. Robots in the case of the article, helped a man to overcome loneliness. The man saw it as that robots could definitely help out more than a human being. Robots initially found work say as, building cars in a factory they have now moved into the home in the form of Roomba the robotic vacuum cleaner and digital pets such as Tamagotchis and the Sony Aibo.

Authenticity

carms — Thu, 05 Nov 2009 13:02:32 CST

Authenticity means establishing the user’s identity beyond reasonable doubt. Authenticating the user is crucial in many situations, particularly in business and legal matters. A simple example of authentication is user login onto a network. A more advanced example would be the use of encrypted digital signatures in a business transaction.

In The News

Policies and Standards

carms — Thu, 05 Nov 2009 13:01:39 CST

Policies and Standards are enforceable measures intended to promote appropriate use. They can be developed by governments, businesses, and private groups or individuals. They normally consist of rules governing access to, or use of, information, hardware and software. For example, a national policy on IT security would need to define what constitutes unlawful access to networks and how to treat transgression. Policies also affect the exchange of information, for example, by making it subject to copyright laws. In general, policies can promote or restrict access, modify behaviour or require the fulfillment of certain conditions prior to or during use. Standards are social or technical rules and conventions that enable compatibility and therefore facilitate communication or interoperability between different IT systems and their components. They might govern the design and use of hardware, software and information. For example, communication protocols used on the Internet, the ASCII representation for characters, or the design of the printer port on a personal computer are all governed by standards.

In The News

Globalization and Cultural Diversity

carms — Thu, 05 Nov 2009 13:01:10 CST

Globalization and Cultural Diveristy means the diminishing importance of geographic, political, economic and cultural boundaries. IT has played a major role in reducing these boundaries. For example, any dramatic event anywhere in the world can be broadcast almost instantly by television or on the Internet. However, there is a fear that easier communication can become a source of cultural homogeneity. The new global village provides a worldwide cultural awareness, but may lead to less diversity.

In The News

Control

carms — Thu, 05 Nov 2009 13:00:53 CST

As an instrument of control, IT improves reliability, accuracy and speed of systems. However, it can also be used to control people. An automatic aircraft landing system provides an example of increased reliability resulting from IT control. Employer surveillance of employees represents a new kind of control imposed on people.

In The News

Equality of Access

carms — Thu, 05 Nov 2009 13:00:36 CST

IT has the potential to offer universal access to information, regardless of distance, age, race, gender or other personal characteristics. However, the above characteristics, and cost, can also bar individuals or groups from access. For example, while telelearning brings previously unavailable opportunities to everyone’s doorstep, the cost of hardware, software or course fees might place the learning beyond the reach of an average person.

In The News

Intellectual Property

carms — Thu, 05 Nov 2009 13:00:17 CST

Intellectual Property includes ideas, discoveries, writings, works of art, software, collections and presentations of data. Copyrights, trademarks and patents legally protect intellectual property, but easy and accurate duplication methods made available by IT can undermine such protections. On the other hand, the same methods create opportunity for inexpensive dissemination of information.

In The News

Integrity

carms — Thu, 05 Nov 2009 12:59:14 CST

Integrity refers to correspondence of data with itself, at its creation. Data lacks integrity when it has been changed accidentally or tampered with. For example, a hacker might change driver licence data resulting in arrests of innocent people.

In The News

HL Y2 Case Study 2010

carms — Fri, 23 Oct 2009 08:59:42 CDT

The ITGS case study, Healthcare in an East African Country, is the stimulus material for the research
investigation required for May and November 2010 higher level paper 3. All of the work related to the
case study should reflect the integrated approach of instruction
.
Candidates should consider Healthcare in an East African Country with respect to:
• relevant IT systems in a social context
• both local and global areas of impact
• social and ethical impacts on individuals and societies
• current challenges and solutions
• future developments.

Candidates are expected to research real-life situations similar to Healthcare in an East African Country
and relate their findings to first-hand experiences wherever possible. Information may be collected through
a range of activities: primary and secondary research, field trips, guest speakers, personal interviews and
e-mail correspondence.

Candidates are expected to research the vocabulary and concepts that are related to the IT technologies in
the case study.

Responses to examination questions must reflect the synthesis of knowledge and experiences that the
candidates have gained from their investigations. In some instances, additional information may be
provided in examination questions to allow candidates to generate new ideas.

Helpful Notes:
The most IMPORTANT thing with all your research is you remember specific real world examples and solutions that you can quote and explain within your examination!

Don't forget the Economic CHALLENGES - check this interesting article on billions lost in E-Healthcare schemes- http://www.thestar.com/news/ontario/article/703083

New article can you believe most hospitals in the UK are only just getting EMR - so how might that effect your views for Africa?

And theres more - check out use of social media in Healthcare?

Remember MIT's wonderful course page on Health Sciences and Technology - Especially good on Future Tech.

ITGS Home

carms — Fri, 16 Oct 2009 10:15:00 CDT

Welcome to the ITGS Wiki at Bowie High School

HL Y2 Candidates 2010	SL Candidates 2010	HL Y1 Candidates 2011

HL Y2
Candidates 2010

SL Candidates 2010

HL Y1
Candidates 2011

HL Year 2 Graduates 09	SL Candidates 09 not pictured: Dung and Eboni

HL Year 2 Graduates 09

SL Candidates 09
not pictured: Dung and Eboni

This ITGS wiki is a collaborative resource project designed to be used by I.B. Information Technology in a Global Society (ITGS) students at James Bowie High School. We will all be contributing to the contents of this site as it relates to IT in a Global Society. The objective of this collaberative project is to use and develop higher order thinking skills, co-operative learning procedures and interpersonal skills in a project based learning environment.

Important Links:

Howstuffworks.com
celestearms.com
Nettrekker Web Portal

**Special recognition goes to Dung Doan, 2009 SL student for designing the banner.

Videos

carms — Wed, 14 Oct 2009 14:32:49 CDT

Beware of Wikipedia

Biometrics

What is Web 2.0?

Wireless Devices

Example of Podcasting--Case Study

Cyber bullying

Megan Meier Story--Cyberbulling CNN

ABC News: Bullying Story

Mobile Broadband's Impact on Health and Society

Network Communication Standards

Skylar_010 — Wed, 23 Sep 2009 20:03:40 CDT

About Network Communication Standards.
For the different types of networks to be able to communicate within it each other the networks have to use similar techniques of moving data through network from one application to another.

A network standard defines guidelines that specify the way computers access the medium to which they are attached the speeds used on different types of networks, and the types of physical cable and/or wireless technology used.

Types of Networks

Ethernet: network standard that specifies no central computer or device on the network (nodes) should control when data can be transmitted; that is, each node attempts to transmit data when it determines the network is available to receive communications. Also based on a bus topology but can be wired in a star pattern

Advantages: Most popular network for LANs, inexpensive, easy to install, and easy to maintain

Disadvantages: Two people cannot use it at a time.

Token Ring: specifies that computers and devices on the network share or pass a special signal in an unidirectional manner and in a preset order. A token is a special series of bits that function like a ticket. The device with the token can transmit data over network only one token exist per network. This ensures that only one computer transmits data at a time.

Based on a ring topology but it can be used as a star topology

Disadvantages: Token passing is sometimes very difficult to understand. It is Network planning required, difficult to physically install, difficult troubleshooting, it is very expensive

Advantage: Deterministic in nature

TCP/IP: Short for Transmission Control Protocol/Internet Protocol; a network standard that defines how messages or data are routed from one end of the network to the other, ensuring the data arrives correctly

Advantages: divides messages into smaller pieces called "packets", which provides an address for each and checks and detects errors and regulates the flow of messages along the network.

(Wi-Fi): Wi-Fi is a series of network standards that specifies how two wireless devices communicate over the air with each other. Wi-Fi certifies products are guaranteed to be able to communicate with each other. Wi-Fi also supports much faster data transfer rates, allows a network many computers and devices together.

Advantages: easily integrate with wired Ethernet networks, ability to connect to the Internet with their wireless computers and devices. Free from interference. Also it has a quick and comfortable installation, also a cheap way to achieve the desired connections with its surroundings.

Disadvantages: In some areas you may need to install extra antennas, it does not require a license in most countries provided that it stays below limit of 100mW which accepts interference with other sources, have a limited range, access points could be used to steal personal information transmitted through Wi-Fi consumers.

Bluetooth: a network standard, specifically a protocol, that defines how Bluetooth devices use short-range radio waves to transmit data. Bluetooth is designed for limited data transfer between two devices, one of which is usually a mobile device.

Bluetooth can be used to wirelessly synchronize and transfer data among devices. Bluetooth can be thought of as a cable replacement technology

Advantages: free from cables and implicity in networking

Disadvantages: poor data rate and security, Bluetooth only offer 1MBps while Infrared offers 4MBps.

RFID: Radio wave identification is a standard, specifically a protocol, that defines how a network uses radio signals to communicate with a tag placed in or attached to an object, animal, or person.

Active RFID tags: contains a battery that runs the chip's circuitry and broadcasts a signal to the RFID reader.

Passive RFID tags: does not contain a battery and thus
cannot send a signal until the reader activates the tag's
antenna by sending out electronic waves. Small enough to
be embedded in skin because it does not contain a battery.

How It Works: The transponder, or tag, consists of an antenna and a memory chip that contains the information to be transmitted through the radio waves. An RFID reader called an transceiver, antenna, reads the radio signals and transfers the information to a computer or computing device.

Advantages: Technology is better than bar codes it cannot be easily replicated, therefore it increases the security of the product. Can store data up to 2 KB.

Disadvantages: Difficult to read tags installed in liquid and metal products. Walkie- talkies, Mobile cell phone towers, and forklifts can sometimes interfere with the radio waves.

WiMax: Short for World Wide Interoperability for Microwave Access,also known as 802.16, a network standard developed by IEEE that specifies how wireless devises communicate over the air in a wide area.

How it works: computers or devises with built-in WiMAX wireless capability or the appropriate wireless network card or PC Card communicate with other computers or devises through a WiMAX tower. The tower can cover up to a 30 mile radius, connects to the Internet or to another Wimax tower. A wireless industry association with more than 240 suppliers and service providers dedicated to developing specifications and testing equipment. Data transfer rate from 54 Mbps to 70 Mbps.WiMAX standard provides wireless broadband Internet access as a reasonable cost over long distances to business and home users.

Advantages: single station can serve hundreds of users. Much faster deployment of new users compared to wired networks. It is standardized, and sane frequency equipment should work together.

Disadvantages: line of site needed for longer connections. weather conditions like rain can interrupt the signal. Other wireless equipment can cause interference. Very power intensive, requires strong electrical support. Has a big installation and operation cost.

(WAP): The Wireless Application Protocol is a standard, specifically a protocol, that specifies how some wireless devices such as smart phones and PDA's can display the content of Internet services

Advantages: WAP uses client/server network

Tree Topology

Shortalmainway — Wed, 23 Sep 2009 19:26:18 CDT

WHAT IS TREE TOPOLOGY?

→Tree Topology the combination of the Bus Topology and the Star Topology. The tree like structure allows you to have many server on the network, and you can branch out the network's in many ways.

(This diagram illustrates the tree network topology. A tree topology integrates the star and bus topologies in a hybrid approach to improve network scalability.)

HOW IS TREE TOPOLOGY USE?
→ Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.
→ Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

ADVANTAGES OF TREE TOPOLOGY:

A Tree Topology is supported by many network vendors ad even hardware vendors.
A point to point connection is possible with Tree Networks.
All the computers have access to the larger and their immediate networks.
Best topology for branched out networks.

DISADVANTAGES OF TREE TOPOLOGY:

In a Network Topology the length of the network depends on the type of cable that is being used.
The Tree Topology network is entirely dependant on the trunk which is the main backbone of the network. If that has to fail then the entire network would fail.
Since the Tree Topology network is big it is difficult to configure and can get complicated after a certain point.

SOCIAL AND ETHICAL ISSUES : Reliability: The tree topology networks is entirely dependant on the trunk union is the main backbone on the network.If that would ever fail then the entire network would fail.

Sources:
http://www.exforsys.com/tutorials/networking/tree-topology.html
http://fcit.usf.edu/Network/chap5/chap5.htm
http://www.edrawsoft.com/Network-Topologies.php

Ring Topology

psychoCHAN — Wed, 23 Sep 2009 03:42:49 CDT

what is Ring Topology?

A ring topology is a network topology or circuit arrangement in which each network device is attached along the same signal path to two other devices, forming a path in the shape of a ring. Each device in the network that is also referred to as node handles every message that flows through the ring. Each node in the ring has a unique address. Since in a ring topology there is only one pathway between any two nodes, ring networks are generally disrupted by the failure of a single link.

How does it used?

The redundant topologies are used to eliminate network downtime caused by a single point of failure. All networks need redundancy for enhanced reliability. Network reliability is achieved through reliable equipment and network designs that are tolerant to failures and faults. The FDDI(Fiber distributed data interface) networks overcome the disruption in the network by sending data on a clockwise and a counterclockwise ring. In case there is a break in data flow,the data is wrapped back onto the complementary ring before it reaches the end of the cable thereby maintaining a path to every node within the complementary ring.

Advantage of using Ring Topology

1.An orderly network where every device has access to the token and the opportunity to transmit

2.Under heavy network load performs better than a start topology.

3.To manage the connectivity between the computers it does not need network server

Disadvantage of using Ring Topology

1.One malfunctioning workstation can throw away the entire network.

2.Moves, adds and changes of devices can affect the entire network .

3.It is slower than an Ethernet network.

Social and Ethical issue

As it stated above, adding and changing of the computer can effect the
other computers that are connected from it. If a person have a basic knowledge of
computer, it is easy to get, or edit the information from the other computer, and
this can effect equality of access. Also the flow of the data is only from one
direction or the other, some people can take this as advantage and restrict or control the data from coming in to their computer.For example, the main computer can be set to restrict curtain information that can be valuable to others.

References
http://bettscomputers.com/moodle/course/view.php?id=14&topic=13&MoodleSession=4eb9f46a1e367006c28141e1591c45a5
http://fallsconnect.com/topology.htm
http://www.businessdictionary.com/definition/ring-topology.html
http://www.geocities.com/doyetech/network.htm

Wired Networks

psychoCHAN — Wed, 23 Sep 2009 03:41:27 CDT

What is Wired Networks?

A wired network is a method that with wires & cablesCoaxial cable, special grades of
twisted pair wires, phone lines or Fiber optic cable and network adapters connect the device called
modem.

How it Works?

There is two gerneral ways to connect wired network. dial-up and DSL

Dial-up

Dial-up Internet access is a form of internet access telephone lines. The user's computer or router uses an attached modem connected to a telephone line to
dial into an internet service provider's (ISP) node to establish a modem to modem link, which is then used to route internet protocol packets between the user's equipment and hosts on the internet, there for dial-up requires time to establish a usable telephone connection. however, this method of connection is very slow, and telephone will not function if the internet is on.

DSL
DSL is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL can be used at the same time and on the same telephone line with regular telephone, as it uses high frequency bands, while regular telephone uses low frequency. DSL typically works by dividing the f requencies used in a single phone-line into two primary "bands" and the user typically installs a DSL filter on each phone outlet. This filters out the high frequencies from the phone line so that the phone sends or receives
only the lower frequencies, and the user hears only the human voice.
The DSL modem and the normal telephone equipment can be used
simultaneously on the line without interference from each other provided that
filters are used for all voice devices.

Advantages

Provide more security
Provides the ability to move large amounts of data quickly
Faster then wireless networks
Typically more affordable then wireless networks
Superior Performance

Disadvantages

Time-consuming and difficult to run cables under the floor or through walls
Especially when computers sit in different rooms
Loose cables likely remain the single most common and annoying source of failure in a wired network
Wired LANs utilizing hubs can suffer performance slowdown if computers heavily utilize the network simultaneously
Wired Ethernet hubs and switches do not support firewalls
Limited Mobility

References

http://computer.howstuffworks.com/home-network2.htm

http://compnetworking.about.com/cs/homenetworking/a/homewiredless.htm

http://search.aol.com/aol/imageDetails?s_it=imageDetails&q=dsl&img=http%3A%2F%2Fwww.netstartel.com%2Fdsl%2Fimage%2Fdiagram_dsl_speedstream.gif&site=&host=http%3A%2F%2Fwww.walkerfirst.com%2Ftechnology%2FDSL_Modems.html&width=124&height=83&thumbUrl=http%3A%2F%2Fimages-partners-tbn.google.com%2Fimages%3Fq%3Dtbn%3ADg3A6yY7MnDbrM%3Awww.netstartel.com%2Fdsl%2Fimage%2Fdiagram_dsl_speedstream.gif&b=image%3Fs_it%3Dtopsearchbox.imagehome%26q%3Ddsl%26oreq%3Dd3daca664448478497bde15800edcf7a&imgHeight=267&imgWidth=400&imgTitle=%3Cb%3EDSL%3C%2Fb%3E+Modems&imgSize=29824&hostName=www.walkerfirst.com

Physical Transmission Media

Shortalmainway — Tue, 22 Sep 2009 20:44:47 CDT

How does it work?

Physical transmission media use wire, cable, and other tangible materials to send communications signals. They include twisted-pair cable, coaxial cable, and fiber-optic cable.

Twisted-Pair Cables consist of one or more twisted-pair wires bundled together. Each twisted-pair wire consists of two separate insulated copper wires that are twisted together to reduce noise, which is an electrical disturbance that can interfere with communications.
Advantages: It is easy to string, and very cheap!
Disadvantages: Subject to noise

Coaxial Cables consist of single copper wires surrounded by at least three layers:
1) an insulated material
2) a woven or braided material
3) a plastic outer coating.
Advantages: Not susceptible to interference, and transmits faster
Disadvantages: It is heavy and bulky. Needs a booster over longer distances.It is heavy and bulky.

Both Twisted Pair Cables and Coaxial Cables send data through electric frequencies.

Fiber-Optic Cables consist of dozens or hundreds of hair-thin strands of glass or plastic, called optical fibers that carry data as pulses of light. Each optical fiber cable is insulated with glass cladding and a protective coating surrounding each optical fiber.
Advantages: They carry more signals than the two above cables, which allows for faster data transmission. It is also less susceptible to noise from other devices, and it is much smaller, thinner, and more lightweight.
Disadvantages: But with great advantages come great cost; it is the most expensive out of the three cables. It is also much harder to install and modify.

What's it used for?Most physical transmission media is used either within or underground between buildings. Ethernet and token ring LANs often use physical transmission media, as well. Twisted-pair cables are mainly used for network cabling and telephone systems. Coaxial Cables are usually used for Cable Television (CATV), because it can be cabled over longer distances than twister-pair cables. It is not as well-used anymore because fiber-optic cables transmits data at much faster rates. Fiber-optic cables are used in businesses and as a backbone for bus topology .

Wireless Transmission Media

Sydney_0911 — Tue, 22 Sep 2009 14:44:45 CDT

What is it?
A wireless transmission media uses radio waves and infrared light waves as a medium for their signals to be able to transfer data, that way they will not be forced to be constricted by cords and will in turn have a larger range of consumers that they can service. Examples of wireless transmission media are infrared, broadcast radio,cellular radio, communications satellite, and a microwave.

How Does it Work?
Wireless transmission media enables computers to send data using radio waves or infrared light. Infrared is a wireless transmission medium that sends signals using infrared light waves. Broadcast radio is a wireless transmission medium that distributes radio signals through the air over long distances such as between cities, regions, and countries, and short distances such as within an office or home. Cellular radio is a form of broadcast radio that is used widely for mobile communications, specifically wireless modems and cellular phones. Microwaves are radio waves that provide a high-speed signal transmission. A communications satellite is a space that recieves microwave signals from an earth-based station, amplifies the signals, and broadcasts the signals back over a wide area to any number of earth-based stations.
Advantages

It is convenient
It is very versatile in that you can easily move from place to place with no restraints
It usually runs a little faster than a standard connection

Disadvantages

It is a little bit more expensive to change a regular connection to a wireless one
It is easier to hack into a wireless network than a standard connection

Sources

http://www.measureup.com/testobjects/ms_netess/5a671dd.htm

Star Topology

chocolatereena — Tue, 22 Sep 2009 14:41:05 CDT

By Reena Anthraper

What is Star Topology?
In a star network, each node is connected to a central device called a hub,which takes a signal that comes from any node and passes it along to all the other nodes in the network. Home networks usually use the star topology.A node can be anything from a computer to a printer.

How does it work?
Any data that is passed from one "node" to another is passed via the central hub before reaching its destination. the hub controls all functions of the network. This type of topology can be used with coaxial or fiber optic cable.

Disadvantages:
-Compared to the bus topology, a star network usually requires more cable.
-If the Hub fails, the whole network fails.

Advantages:
-It can be used for large networks, not just the home, because it is easier to expand.
-With this particular topology, the problems are easier to fix because they isolate themselves.
-If a failure were to occur in any of the cables, it will only take down one computer's network access and not the entire network, where as in a bus topology, where multiple terminals crash.

Social and Ethical Implications
There are three types of hubs:
A passive hub serves simply as a conduit for the data, enabling it to go from one node to another.Passive hubs seem to be the best type of hub to use when trying to create a network for small businesses or homes, because they are just conduits; they do not use much intelligence to move around data from one to another. But that can also serve as a problem. It can make copies of the information and send it to all connected nodes. For instance, if one node decides to post an objectionable picture, they all the other nodes have the possibility of getting it. Also, if one node decides to do their taxes on that particular computer, then all the other computers can obtain that same tax information.

intelligent hubs (manageable hubs) include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub.
Intelligent hubs allows administrators to monitor all the data passing through between nodes. Although it can be used as a preventive measure to avoid possible lawsuits or problems within the work environment, it can also be considered a leakage of privacy. Users of the nodes will essentially have "Big Brother" watching them.

a switching hub actually reads the destination address of each packet and then forwards the packet to the correct port. Switching hubs can have problems of reliability. It reads each packet of data and forwards it to the corresponding node. If it is private information, and the hub misreads the packet of data and sends it to the wrong node, huge issues can result. For example, if an administrator of a company tries to send an email to an employee stating that the employee is fired, but the switching hub gives it to the wrong node, and a different employee receives the email, then huge miscommunication issues can result from the unreliability of a switching hub.

Sources:
http://computer.howstuffworks.com/lan-switch2.htm
http://compnetworking.about.com/od/networkdesign/a/topologies.htm
http://fallsconnect.com/topology.htm
http://www.webopedia.com/TERM/H/hub.html

Network Topology

Sydney_0911 — Mon, 21 Sep 2009 15:12:20 CDT

What Is Network Topology?

Network Topology is the configuration of cables, computers and other peripherals. It is also "the layout of connected devices" and is often seen as "the shape or structure" of a network. The network topology plays a crucial part in the design of the network.

The definition of network topology is:

The specific physical, i.e., real, or logical, i.e., virtual, arrangement of the elements of a network. Note 1: Two networks have the same topology if the connection configuration is the same, although the networks may differ in physical interconnections, distances between nodes, transmission rates, and/or signal types. Note 2: The common types of network topology are illustrated [refer to the figure on this page] and defined in alphabetical order below:

Factors to Consider When Choosing a Topology?

Money. The installation of some topologies can be very costly if you have to purchase concentrators. We all know that the economy is not at its best right now and that it is important for the average american to save that extra buck or two.
Length of cable needed. This is important because the longer the cable is then the more likely it is that their is a break in the main cable which will cause the whole network to shut down.
Future growth. With a certain topologies, expanding a network is easily done by adding another concentrator. this is convenient because it makes it easier to give your network more memory .
Cable type. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.
Are you using low-bandwidth connections from remote sites? because if the bandwidth is too high for your computers then it can slow it down so that is why it is good to try to use a low bandwidth.
Are all your users in one site, or are they scattered across the world?
How congested is your current network? because if you are dealing with a very high activity server then it can make your computer run very slow.

Advantages and Disadvantages

by using the programs it makes it alot easier to desigfn things on your computer.
they can get fairly costly if you want a quality server
on certain topologies you can disconnect your entire network based on one cord
it is very easy to give your topologies more memory and storage space.

Sources:
http://compnetworking.about.com/od/networkdesign/a/topologies.htm
http://www.its.bldrdoc.gov/fs-1037/dir-024/_3535.htm
http://fcit.usf.edu/Network/chap5/chap5.htm
http://search.aol.com/aol/image?s_it=topsearchbox.imagehome&q=Network+Topology
http://www-10.lotus.com/ldd/stwiki.nsf/dx/network-topology-considerations

Types of Topologies:

Basic Hardware and Networks

carms — Mon, 21 Sep 2009 14:38:30 CDT

System Fundamentals

Biometrics

Networks

Wired
Physical Transmission Media
Wireless
Wireless Transmission Media
Network Topology
Types of Topologies:
bus
ring
star
tree
mesh
Network Architecture
Network Communication Standards