Unit 1.4 - Wired And Wireless Networks
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Stand-Alone Pc
Computer that is not connected to any other device, network or the internet.
A Network
Two or More Computers connected together
Advantages of - Network
• Share Hardware (Printers) - - Share Files • Log on anywhere • Central Backups • Central Virus checks
Disadvantages of - Network
• Viruses & Hackers • Network Failure & Traffic • Costs of Hardware & Software needed • Expert Knowledge & Skills needed
LAN
Local Area Network Small geographical location
WAN
Wide Area Network Large geographical location (Network of Networks)
A Switch
Links Computers and Peripherals in an LAN Switch - Sends data only to device needed
A Hub
Links Computers and Peripherals in an LAN Sends data to all devices More Data Collisions, Slower Network, Cheaper, Security Risks
Network Interface Card (NIC)
Needed in Every Device / Peripheral to connect to a Network MAC Address
Router
Receives, Forwards, Directs data packets between Networks & Computer
Wireless Access Point
Links computers & peripherals Wirelessly
Modem
Modulator Demodulator Converts analogue signals to digital and back again
Bridge
Connects two separate LAN Networks. Relays data to receiving computer.
Server
Responds to request for data Stores data used by other computers on a network
Ethernet
Twisted Pairs of Cables Cat-5, Cat-5e, Cat-6 Cheap, Sturdy Short Distance (100m) & EMI/RFI Interference, Slower
Coaxial Cable
Insulated Central Wire Braided wire shield to Prevent Interference Cheap, Long Distances EMI/RFI Interference
Fibre Optics
Glass Threads Transmit Light as Data Fast Bandwidth (10 Ghz), Secure, Long Distance, No Interference Expensive, Brittle
Client-Server Network
Client makes requests to the server for Data, Access & Programs.
Peer-to-Peer Network
All Computers are Equal Peers download/share different parts of the same file.
Network/Wired Performance
Transmission Used (Fibre or Copper) Number of Users Bandwidth Error Rate Latency
Wireless Performance
Frequency Range Channels Used / Sharing Channels Distance from WAP Physical Obstacles (Thick Walls, Metal) Non-Wifi Interference (Microwaves, Cordless Phones)
Bandwidth
How much data can be transferred over a connection in a given time
Latency
How much Delay in sending and receiving bits.
Error Rate
How many data errors happen over a given time. Sending a 0 instead of 1 Caused by Weak signals over longer distances Or Electromagnetic / Radio Frequency Interference