Networks

Networks

1. Services

   • Internet - the internet is a WAN which is made up of many other smaller networks
   • Extranet - an external network which can be viewed by many different people at an organisation such as employees, suppliers and shareholders
   • Intranet - an internal network which is private to one organisation, viewable to employees only
   • Routers - these are used to allow different networks to communicate. they can connect a network in a home to a wider network such as the internet
   • Switches - usede to connect different computers together as part of a network
   • Gateways - they allow two different networks to speak to one another by translating data
   • Bridges - these are used to join - or bridge - two LANs together to form one larger network
   • Packet Switching - switches can speed up networks by only sending packets of data to the computers which need the data. this means that less data is travelling unnecessarily around the entire network
   • advantages and disadvantages of using networks over stand-alone computers
     • Advantages - data can be shared making it easierto work together. computers canshare hardware like printers - no need to buy more than one so its cheaper. its quicker to update software - it is stored in one place on a server
     • Disadvantages - viruses can easily spread through networks. if data and software is all on one place, all computers will not work if the network experiences problems. networks require regular maintenance - this is expensive

2. Key Words

   • LAN
     • Local Area Network
     • suitable for smaller areas such as single companies or organisations
     • join together computers in different ways called network topologies
   • WAN
     • Wide Area Network
     • available over very large areas in many different organisations
   • Intranet
     • a WAN which is made up of many other smaller networks
   • Extranet
     • an external network which can be viewed by many different people at an organisation such as employees, customers, suppliers and shareholders

3. Topologies

   • ring topology
     • all networked computers are connected together in a circle
     • this is fast because, unlike with a bus network, all data travels one way down the cable
     • the disadvantage is that if one cable breaks, all the computers will not work
   • bus network
     • bus networks join all computers to one big cable called the backbone
     • they are very cheap and easy to install, but if the backbone breaks, the whole network is unavailable
     • this network topology is not suitable for large LANs because too many computers can slow down the network
   • star network
     • all computers are connected directly to a server using hubs or switches
     • this is good because if one cable breaks, all others still work
     • its fast as each computer has its own line to the computer
     • a disadvantage is that it is expensive to buy the hardware like hubs and switches

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