Network connections

• Routers connect networks together by forwarding data packets between them based on their destination addresses.
• A network is a group of computers that are connected to one another.
• Switches are used to interconnect devices within the same network, allowing multiple devices to communicate with one another.
• Networks can be wired or wireless, with the latter being more convenient but potentially less secure.
• Wireless networks use radio waves to transmit signals over short distances without cables.
• Network connections


  To connect devices together in a network, either some kind of wired or wireless connection will be necessary
• Types of cable


  • Coaxial
  • Twisted pair
  • Fibre optic
• Coaxial cable


  • Copper cable that has a central wire surrounded by an insulating layer
  • They have an outer layer that acts as a jacket
  • Used to carry out frequent radio signals
  • Used in applications such as TV and cable TV connections and some internet connections
• Coaxial cable


  • Advantages: Low manufacture and purchase cost, Lower error rate as the central wire is within a faraday shield (a special shield used to block electromagnetic interference)
  • Disadvantages: Has the lowest level of bandwidth of the three cables, The way in which a coaxial cable is insulated can make it difficult to install and maintain
• Twisted pair cable


  • Type of copper cable that has two insulated wires
  • Covered with an outer layer that acts as a jacket
  • They transmit electric current
  • Used for telephone communications and normally as part of an ethernet network
• Twisted pair cable


  • Advantages: Crosstalk (a signal transmitted from one channel to another) is minimized, Lowest cost to manufacture and produce, Higher level of bandwidth than coaxial
  • Disadvantages: Can be subjected to electromagnetic interference, Has the shortest distance that a signal can be carried before it will begin to deteriorate
• Fibre optic cable


  • Cable that is made up of many fine threads of glass, they are covered in an outer layer
  • They can transmit data quickly
  • They use the properties of light to transmit data
  • Used in modern internet connections and in high performance networks where large amounts of data are transmitted
• Fibre optic cable


  • Advantages: Has the highest level of bandwidth available of the three cables, Can carry signals for a much longer distance without deterioration
  • Disadvantages: High manufacturing and purchase cost, Can be difficult to install due to fragile glass tubes
• Wi-Fi


  • Uses radio signals
  • Most common wireless network connection
  • Each device that wants to make a wireless connection will broadcast a radio signal. A router or WAP (wireless Application Protocol) will receive these signals and process them
  • The router/WAP will also broadcast radio signals that will be received and processed by each device when it receives data that has been transmitted
  • Wi-Fi currently transmits data at frequencies of 2.4 GHZ and 5 GHz, which are considered high frequencies
  • The current limit for Wi-Fi data transmission is approx. 450 Mbps
• Wi-Fi


  • Advantages: Several wireless capable devices can connect to a single router/WAP, High level of frequency means that large amounts of data that can be transmitted at a time, Has quite a large range of approximately 100m
  • Disadvantages: Less secure than a wired connection, Radio signals can be subject to interference
• Bluetooth


  • Bluetooth also uses radio signals to create a wireless connection between two devices
  • Uses radio frequency 2.45 Ghz.
  • Devices need to be within 10m of each other to establish a connection
  • There is currently a limit of eight devices
  • The two devices requesting a wireless connection using Bluetooth must have matching profiles to stop pointless connections being made, e.g. connecting a wireless mouse to a digital camera
  • To connect, devices transmit radio signals and receiver devices which have a matching profile within range will pick up the signals and identify the sender.
  • It may require a pin code
• Bluetooth


  • Advantages: Requires a low level of power consumption, Doesn't require a line of , so it can work through obstacles, Can be made more secure by requiring a pin code for connection
  • Disadvantages: Has a limit of 10m for connection, There is a limit of eight devices, Has a lower level bandwidth available than Wi-Fi
• Infrared


  • Use infrared radiation as its method of connection
  • There are two types: Line-of-sight: There must be a direct line of sight between the sending device and receiving device so there are no obstacles in the way. Scatter mode: A device broadcasts infrared into a certain area and any device may receive it directly or through reflection of an obstacle. The sending device will need the ability to produce an infrared signal and the receiving device needs an infrared sensor
  • They can also be used to transmit data from one device to another in a network. The infrared laser beam must have a direct line of sight in order to connect to devices
  • It is similar to fibre optic in the sense that it uses properties of light to transmit data
• Infrared


  • Advantages: Most secure form of connection, Low cost to manufacture and purchase, Requires a low level of power consumption, It doesn't get any interference from radio frequencies
  • Disadvantages: Cannot be transmitted through obstacles, If line-of-sight is used, there must be a direct line of sight between the two devices, Can only be used to connect two devices, Has a short range with a limit of approximately 1m
• Wireless connections


  • Do not have the same level of protection as wired connections
  • Wired connections are often secured with locks and other methods
• Protocols to improve wireless network security

  • Wired equivalent privacy (WEP)
  • Wi-Fi protected access (WPA)
• WEP


  Provides a wireless network with a compatible level of security to a wired LAN by encrypting data transmissions
• WPA


  Standard required of devices with a wireless internet connection. It is designed to provide a more sophisticated encryption method than WEP
• Microwaves


  Have shorter wavelengths, so they are generally used for short-distance communications
• Radio waves


  • Have longer wavelengths, so they are generally used for long-distance communications
  • The waves used in Wi-Fi and Bluetooth are technically microwaves but the term radio waves is more commonly used to describe technology used in wireless data transmission