Computer Networks

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Computer Networks
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Why Create Networks?

• Communication
• Communication technologies such as e-mail, sms,
  video-conference can be used
• Makes communication faster, more efficient and
  cheaper
• Data Sharing
• Makes data easy to access and share
• Hardware Sharing
• Expensive hardware resources can be shared
  instead of having to buy more (e.g. printers,
  copiers)
• Internet Access and Internet Access Sharing
• Allow access to the wide variety of resources
  available on the Internet
• Allow an Internet connection to be shared among a
  group of computers instead of 1 connection for
  each
• Data Security and Management
• Centralizes the storage of information
• Controls can be placed on the storage and access
  and backup of information

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Network Types

• Local Area Networks (LANs)
• A group of computers connected in a small
  geographical area
• An example is the St. Mary School network
• Wide Area Networks
• Is a network that covers a wide geographical area
• The most well known example is the Internet

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Making the Connection

• The most common types of network communication
  are
• Twisted Pair Cable
• Fibre-Optic Cable
• Wireless (WiFi)

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Twisted Pair Cable

• This is the most common type of network cabling
• Within the cable are 4 pairs of twisted wires
  carrying electronic signals
• Maximum distance 100m
• Max speed of 1000Mbps

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Fibre-optic Cable

• Data is transmitted along very thin fibres of
  glass using pulses of light
• It can carry data over long distances (many km)
• It is more expensive to purchase and install than
  twisted pair
• Max speed of approx. 1000Mbps

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Wireless (WiFi)

• Uses radio transmissions
• Indoor range is approx 30-70m
• Can be used in places wires may be difficult or
  impossible to run
• More susceptible to signal loss than a physical
  cable
• Max speed of 150Mbps (N) or 500-1000Mbps (AC)

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Directing Network Traffic

• In order for your network to function, it needs
  to be able to pass information from node to node
• Ideally, this would be done as efficiently as
  possible
• The basic types of hardware that are used to do
  this are
• Switches
• Routers

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Switches

• Send messages to the appropriate computer
• Used to create LANs

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Routers

• Provide a boundary between networks
• Used to create and access WANs

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Wireless Router/Switch

• Two main types available
• 802.11b (older 11 Mbps speed)
• 802.11g (older54Mbps speed)
• 802.11n (current 150Mbps speed)
• 802.11ac (newest 500-1000Mbps speed)
• Capable of sending signal everywhere inside a
  house
• Speed can be doubled using some hardware
  combinations

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A Typical Network
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Servers

• Servers provide services to devices on the
  network
• Common types
• Mail
• File server
• Application Server
• DNS (Domain Name System)
• DHCP (Dynamic Host Configuration Protocol)
• Database server
• Web Server