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Topic 5 Computer Networks (Network Connections (WIRED: Fibre Optic (Fast,…
Topic 5 Computer Networks
A computer network is more than one computer or device, connected together so that they can communicate
PAN: Personal Area Network
Usually enables data transfer between 1 person's devices Eg Laptop, Smart Phone, Printer
Usually uses Bluetooth connections
LAN: Local Area Network
Computers connected in one smallish geographical location Eg one room, building, campus
Eg School, Hospital ie usually managed/owned by one organisation
Can use wired and/or wireless connections
WAN: Wide Area Network
Covers a wide area eg city, country, world
Internet is the biggest eg of a WAN
Usually collective/distributed ownership
Network Connections
WIRED: Fibre Optic (Fast, expensive),
Copper wire (Slower, cheaper)
Use fibre from servers to switches (ie most used connections, but fewer)
Use copper from switches to Computers
Wired: more reliable, consistent speed than wireless and more secure
WIRELESS: Need WAPs around a building and wireless network cards per device
Advantages: - no need for additional cabling to extend a network, devices can be used away from network points, mobile devices can be used on the move
Disadvantages: signal strength may different in different locations, slower connection, less secure.
Topologies
STAR:
Each workstation connected to the hub via its own cable
+ve Reliable - damage to a cable only affects one workstation
+ve Very few data collisions
ve Good security as workstations cannot communicate with each other directly - have to go via the hub
-ve expensive due to cabling per workstation
-ve More complex to set up, so technical staff required £££
-ve If hub crashes, no workstation can operate
BUS:
All workstations and peripherals connect to the 'backbone' cable, that has terminators at each end. Data is sent to all workstations and the receiver processes it, the rest drop it.
+ve Easy to install// Easy to add worktations
+ve Less cable needed compared with Star
-ve Proble with central cable affects all devices
-ve If a lot of worktations, data travels slowly
-ve Can be a lot of data collisions
-ve Less secure as all workstations (NOT users) can see all the data
Benefits: Can share resources eg printers
Can share data
Can communicate between devices
Can install and update software on all computers at once
Can central back-up
User accounts - can logon to any computer
Drawbacks:
If a central server fails, all computers may not work
If a virus infects one computer, it may spread across the whole network
Data can be less secure as any computer on the network could be hacked
Can be expensive to install and manage (employ a network manager)