Transfer of data in ICT systemsThis section covers:Elements of a networkCharacteristics of a networkCommunication of data and use of communication technologiesStandard used when communicating data

An ICT network

•Networks are connected by different types of transmission media, such as telephone lines, satellites and optical fibres

•The old differentiation between networks were LAN and WAN (Local area network and wide area network)▫LAN: Local Area Network▫WAN: Wide Area Network

•MAN: Metropolitan Area Network: all connected via a fast line.

What are the characteristics of each network?• A LAN (local area network) is a group of computers and network

devices connected together, usually within the same building. By definition, the connections must be high speed and relatively inexpensive (e.g., token ring or Ethernet). Most Indiana University Bloomington departments are on LANs. For more information on LANs, see What is a LAN (local area network)?

• A MAN (metropolitan area network) is a larger network that usually spans several buildings in the same city or town. An example of a MAN could be a university with multiple campuses within one town.

• A WAN (wide area network), in comparison to a MAN, is not restricted to a geographical location, although it might be confined within the bounds of a state or country. A WAN connects several LANs, and may be limited to an enterprise (a corporation or an organization) or accessible to the public. The technology is high speed and relatively expensive. The Internet is an example of a worldwide public WAN.http://kb.iu.edu/data/agki.html (2007)

Characteristics of Metropolitan Area Network•Businesses can plug into the network at a

high speed•MAN is specific to that area and much

faster•MAN uses optical cable, high speed. •Optical cable is expensive and charged by

how much is required, so although technically, a WAN could also use optical cable, it would be very expensive.

Why are networked computers better for organisations?•Client Server Network allows access to

networked resources. •Make use of shared printers•Central file storage

Intranet vs. Extranet

•Intranet: Internal▫Within the company, employees etc…

•Extranet: External▫For customers, through username and

password▫SharePoint allows access (like Moodle but

specific for organisations as opposed to schools.)

•Both are private networks as authentication is needed to allow access

•Neither are open to the general public

Characteristics of a Peer to Peer Network• In a peer to peer network, the Operating System defines

the shared resources. Internet connection can be shared amongst numerous

computers files can be backed up from computer to computer Equipment can be shared.

• Main computer connects to the internet through an ADSL (Asymmetric Digital Subscriber Line) modem.

• Cheaper than Client Server Network• One of the peers may have the necessary files to be shared• Logging on locally • Users would have to be named to authenticate permission

to share resources.

Client Server Network• A server is used as a central store for resources.• Logging on to the domain, usernames and

passwords are stored centrally on the server and users are added to the domain.

• Better control over permissions with the domain. Member of groups (example, students and teachers.) You can set permission for “all students can access this file” as opposed to naming users individually on a p2p.

• Network switch is used to join computers and specify the user that the transmission is to go to

The Internet

•The internet has been described as a “network of networks” it is a large group of interconnected computers.

•Benefits include the use ability to communicate to other users anywhere in the world.

•Using e-mail•Instant messaging

The World Wide Web (www)

•Is used on the internet.•HTTP: (Hypertext Transfer Protocol) is

what we use within the internet that allows our web browser to access files.

•Web pages are often written in HTML (Hyper Text Mark-up Language.)

TCP/IP

•Transmission Control Protocol and Internet Protocol

•Manage the flow of data via the internet•TCP/IP is generally the de-facto standard

for managing the flow of data.