Networks

Networks

1. LAN

   • Local Area Networks
   • Suitable for smaller areas such as single companies or organisations. Your school network is a LAN
   • LANs join together computers in different ways called network topologies.
     • Network computers are connected togethether in a circle called ring topology.
       • This is fast because all the data travels one way down the cable
       • If the one cable breaks, all the computers will not work.
     • Star Networks
       • All computers are connected directly to one big computer called a server using hubs or switches
       • This is good because if one cable breaks, all of the other cables will still work.
       • It is fast becuase each computer has its own line to the server.
       • It is expensive to buy the hardware like hubs and switches.
     • Bus Networks
       • Joins all computers to one big cable called the backbone.
       • Very cheap and easy to install.
       • 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.

2. WAN

   • WIde Area Networks
   • Available over very large areas in many different organisations. The World Wide Web is a WAN

3. Hardware/services

   • Internet
     • The internet is a WAN which is made up of many other smaller networks.
   • Extranet
     • An extranet is an external network which can be viewed by many different people at an organisation such as employees, customers, suppliers and shareholders.
   • Intranet
     • This internal network 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
     • Switches are used to connect different computers together as part of a network.
   • Gateways
     • These allow two different networks to speak to each other 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 computer which need the data. This means that less data is travelling unnecessarily around the entire network.

4. Advantages

   • Data can be shared, making it easier to work together
   • Computers can share hardware like printers - no need to buy more than one, so it is cheaper.
   • It is quicker to update software - it is stored in one place on a server.

5. Disadvantages

   • Viruses can be easily spread through networks.
   • If data and software is all in one place, all computers will not work if the network experiences problems.
   • Networks require regualar mainternance - this is expensive.

6. Intergrated PoS

   • Handles payment in shops.
   • A barcode reader will scan a barcode
     • The system will automatically find the price and work out how much needs to be paid using a debit card.
       • The debit card is then placed in a chip and pin reader and a printer will automatically print out a reciept.
         • When a product is sold, the automatic stock control system will log this in its database.
           • This database will be connected to a nnetwork and will automatically reorder from suppliers if stock goes too low,