ICT - 4.3.1

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  • Created by: celia_x
  • Created on: 12-03-16 11:57
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  • 4.3.1 - Networks
    • CHOOSING A NETWORK
      • COST
        • Budgetary constraints will determine what can and cannot be purchased
      • SIZE OF THE ORGANISATION
        • Network size can vary from 2-3 computers to a global network. LAN's are self contained, WAN's are based in more than one geographical location
      • HOW THE SYSTEM WILL BE USED
        • Will a wide range of applications be used on the network?
        • Will a large number of files need storing?
        • How will data processing be done? Centralised processing means individual workstations having fewer resources
      • EXISTING SYSTEMS
        • Often networks are built as extensions of existing systems
        • The new system will need to be designed taking into account: communication media, operating system and geographical location
      • PERFORMANCE REQUIRED
        • Network performance can be measured by: speed of processing, user friendliness, capacity and reliability
        • Organisations will prioritise different performance criteria e.g. a data processing company may require fast processing rather than user friendliness
    • TYPES OF NETWORKS
      • CLIENT-SERVER
        • The server stores files and apps required by the clients. Requests are made by the clients to the server and the server responds
          • COMPARISONS
            • For small networks and organisations, less expensive
            • CLIENT-SERVER
              • More expensive
              • Requires technical knowledge
              • Centralised security
              • Ideal for large networks
              • Central backups
            • PEER-TO-PEER
              • Cost saving
              • No network manager
              • Easier to set up
              • No reliance on server
              • Security issues
      • PEER-TO-PEER
        • For small networks and organisations, less expensive
    • NETWORK TOPOLOGIES
      • Describes the physical layout/shape/map of a network or a group of networked computers and how they are linked (cable, fibre optic/wireless)
      • THE BUS TOPOLOGY
        • All computers and nodes are connected to a single cable. Data is transmitted in either direction
        • Advantages
          • Compared to others its the least expensive
          • Easy to install
          • If one workstation malfunctions, others are unaffected
        • Disadvantage
          • Affected by heavy traffic
          • If the whole network cable malfunctions it affects the whole network and is difficult to locate
      • THE RING TOPOLOGY
        • Computers and nodes are linked together in a circular configuration, there is a central host computer
        • Disadvantage
          • If one node malfunctions it will affect the whole network
          • If the link fails the whole system stops working
      • THE STAR TOPOLOGY
        • There is a central computer, called a server/hub, all nodes of the network are connected to it. All data passes through the server/hub
        • Advantages
          • If a node fails the network will continue to function
          • Good transmission speeds can be achieved
          • Ideal for widespread networks
        • Disadvantage
          • If the server/hub fails the whole network is affected
          • Expensive to install, requires extra equipment
    • CHOOSING A SUITABLE TOPOLOGY
      • BUS TOPOLOGY
        • For small networks (especially peer to peer)
          • Where the cheapest solution is required
            • Where the network will remain unchanged (no additional nodes required)
      • RING TOPOLOGY
        • Where there is heavy traffic on the network
          • Where the network needs to be changed
            • Where operating speed is important
      • STAR TOPOLOGY
        • For large networks
          • Where extra client computers need to be added
            • Where easy trouble shooting is required
    • WIRELESS NETWORKS
      • A wireless network is defined as one that uses radio transmission and receiving devices for sending and receiving data
      • USES
        • As part of a LAN e.g. a mobile bar code reader in a warehouse stock control system
        • As part of a WAN e.g. a driver using a hand held device to confirm deliveries to a central database
      • Advantages
        • Inexpensive LAN's to be set up without cables
        • Freedom of working anywhere a signal can be received
        • Ideal for networks on old listed buildings where cables would not be allowed to be installed
        • Can use a variety of devices such as tablets and mobile phones
      • Disadvantage
        • Power consumption is high which means laptops can exhaust their batteries
        • There may be security problems even when encryption is used
        • Wi-Fi networks have a very limited range
        • Transmission speed is slower than cable
    • REMOTE MANAGEMENT
      • The network manager uses the network to perform various tasks
        • Check to see no unauthorised software is loaded onto the machines
        • Update software and rebuild software on stations
        • Guide users through problems
        • Shut down stations/log off users who have forgotten to do so
        • Clear printer queues

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