Networks And Communication Part D

Networks And Communication Part D

1. Bandwidth

   • This is the measure of how much data can be transferred in a time
   • The higher the bandwidth the more data that can be transferred
   • Often measured in Mbps which is bits per second or Mpbs which is bytes per second
   • The more frequencies available on a channel the faster it is

2. Bottleneck

   • A bottleneck is the smallest bandwidth that exists between the user and the place that data is being downloaded from
   • The data even though it may have been travelling more quickly before will get slowed down at the bottle neck

3. Cables

   • Copper Cable
     • Modern copper cables are in twisted pairs, this is narrow wire that is insulated and twisted in twos, without an earth wire- known as a UTP or Ethernet cables, this can sometimes result in loss of data.
     • There are also STP cables, these do have an earth which is a metal shield that reduces electromagnetic interference, these have a higher bandwidth capability so are used in high speed networks
     • Coaxial cables which were used in older networks and is still used in the television industry as it has a capacity for high bandwidth. This has two wires and the outer cable acts as a shield to electromagnetic interference.
   • Optical Cable
     • Fibre-optic cables use small glass tubes to reflect light along the tube
     • These have much higher bandwidth as they do not have any electrical interference
   • Wireless
     • These can be radio, satellite and infra-red.
     • This has a lower bandwidth than the wired methods
     • Can be interrupted by physical obstacles such as walls

4. Importance of bandwidth

   • The importance of bandwidth depends on what it is being used for
   • If something is being streamed then a large bandwidth is needed
   • If something is being downloaded overnight then it does not matter too much as it is going to be used the next morning or day
   • Live/real time data needs a high bandwidth as if it does not then it will freeze and not work well