Networking Classification A network is two or more computers that are connected 1 There size 2 Their Servers

Networking I Processing Steps: Communication Sending information to those who need it using communication applications: videoconferencing websites, fax, voice mail, etc between terminals between computers on a network

Networks can be classified by: Types of networks 1Their Size, LAN, WAN, WLAN, Internet 2Their Servers, Peer-to-Peer; Client/Server; Internet peer- to-peer 3Network Topologies: Bus, Ring, Intranets 4The rules they use to exchange data, Protocols 5Network Security 6How networks are connected, & their hardware

Why Network? 1Efficiency – faster communication, cost savings (compare costs with phone calls, physical travel, shared equipment), staff savings (e.g. one networked helpdesk with remote control of workstations) 2Facilitating communications 3Sharing hardware 4Sharing data and information 5Sharing software 6Transferring funds

Types of networks, by size Local Area Network (LAN) – typically restricted to one building or one site Node, each device on the network Wireless Lan (WLAN); Wireless local area network Network OS, (NOS); system software organising & controlling activities on LAN, eg. Windows Server 2003; Novell and Apple Wide Area Network (WAN) – spread over wide distances Internet – the Network of Networks

Sending and Receiving Devices Telephone line is analog. Computers are digital devices. A Modem is required to send data over a telephone line. Mo – modulate Dem – demodulate; ie. A modem changes the signal from digital to analog and back to digital

LANs – local area Geographically limited, usually to one site. Usually cabled with CAT 5, (UTP), or wireless. Longer distances between buildings may need fibre optic cable.

WANs – Wide Area Wide Area Network (WAN) – broad geographic coverage (e.g. state-wide, country-wide) Connections use landline data cables (e.g. ISDN, ADSL), satellite. Virtual Private Networks (VPN) can form a private network using the internet as a communication channel – much cheaper than leased ISDN lines.

The internet Internetworked WANs. Anarchic and always in flux: defined by the users currently connected to it. Uses all forms of media… UTP, coaxial, fibre optic Satellite Microwave, wireless, mobile phones Modems on voice phone lines High-speed digital data lines (ISDN, ADSL) Submarine cables Mains power lines.

Peer-to-Peer (P2P) networks -No server, so costs are low and installation is simple -All computers and users have equal authority and rights -Little protection of one workstation against another -Used at home or in small organisations with trusted users -Allows sharing of files, internet connection, printer -Internet music sharing networks such as Kazaa are peer-to- peer because there is no central coordinating computer, data and operating software are stored on on each client’s computer.

Internet-Peer to Peer (P2P) networks -- P2P, enabling users with same networking software to connect to each other’s hard disks and exchange files directly -Once connected you have access to their hard disks -Examples, Kazaa and Limewire -Exposure to possible security violations, eg. viruses and trojans

Client/Server -Very common model. A basic function of network computing. -One computer program (the ‘client’) asks another computer program (the ‘server’) to provide a service, such as looking up and providing data, delivering , sending web pages, bank balances etc. -The client/server model can interconnect programs distributed across different locations.

Client/Server -Dedicated server more storage space & power -File server -Print server -Database server -Network server