Slide 1 What is a Computer Network? A computer network is a linked set of computer systems capable of sharing computer power and resources such as printers, large disk drives, CD-ROM and other databases. There are two types of network:  Local Area Network (LAN)  Wide Area Network (WAN)

Slide 2 Local Area Networks A local area network is a computer network across one building or site. Fileserver Printer Work Station Network Cable

Slide 3 Peer to Peer Network This describes a very simple network structure where shared resources such as printers are available but where there are very few other facilities. All computers on the network have similar specification and status.

Slide 4 Client-Server Network This method of network organisation requires one or more servers to which a number of clients may obtain services. The servers act as central resource managers for the network. A star topology is often used for this form of network.

Slide 5 Network Hardware Network hardware will include:  stations  servers file, print, web  passive components cables, connections, etc  active components repeaters, hubs, switches

Slide 6 Network Stations The network station (often called the client) will normally comprise:  PC  Network interface card (NIC). The NIC allows the computer to communicate with the network  Network Operating Systems eg. Windows 2000, Windows NT, Appleshare, etc

Slide 7 Network Servers A network server is a computer which acts as a central storage point for files and applications. Servers also act as a connection point to shared peripherals such as printers.

Slide 8 IP Addressing Every computer station on the internetwork must have an IP address. This IP address must be unique but is not encoded in the network interface. It is set by software in the computer.

Slide 9 Implications of Networks Computer networks have developed as a result of a perceived need and as a result of economic and technical factors. Computer networks have social, legal and ethical implications

Slide 10 Economic Factors The cost of communication technology  equipment costs are continually reducing and improving features mean that more is available for the same money. Access to expensive equipment  printers and mass storage are expensive so it makes sense to share them. Geographic spread of organsiations  video-conferencing and , etc allow organisations to cope with geographic isolation.

Slide 11 Technical Factors Adoption of Internet technology  TCP/IP Adoption of International Standards  ISO OSI Development of Communication Technology  fast modems, ISDN, etc

Slide 12 Social Implications Individuals may become withdrawn from society Personal privacy may be compromised as a result of monitoring network use People may not have to move from rural communities to find Home working may allow strengthening of family life (?)

Slide 13 Ethical Implications Bogus doctors could easily offer medical advice over the Internet. Availability of unacceptable and inappropriate material within education Antisocial, criminal, racist or other prejudiced material may be distributed freely.

Slide 14 Legal Implications Copyright law  British law makes it illegal to copy someone elses copyright material. A lot of material on web pages is copyright Sometimes the breaking of this law is unwitting but in others it is deliberate (eg MP3 files of commercial recordings)