LANs and WANs

• A LAN is a Local Area Network
• A LAN covers a small geographical area located on a single site
• All the hardware for a LAN is owned by the organisation that uses it
• LANs are either wired (e.g. with Ethernet cables) or wireless (e.g. using Wi-Fi)
• A LAN can be wired using Ethernet cables
• A LAN can be wireless using Wi-Fi
• You'll often find LANs in businesses , schools and universities
• Lots of homes have a LAN to connect various devices such as PCs , tablets, smart TVs and printers
• Why use a LAN?

  • Sharing files is easier – network users can access the same files  
  • You can share the same hardware (like printers) on a LAN  
  • The Internet connection can be shared between every device connected to the LAN  
  • You can install and update software on all computers at once, rather than one-by one  
  • You can communicate with LAN users cheaply and easily (e.g. instant messaging)  
  • User accounts can be stored centrally , so users can log in from any device on the network 
• WAN stands for Wide Area Network
• A WAN connects LANs that are in different geographical locations
• A business with offices in 3 different countries would need a WAN for all their devices to connect together
• Unlike a LAN, organisations hire infrastructure (e.g. communication lines) from telecommunications companies who own and manage the WAN - This is because a WAN is more expensive to set up a than a LAN
• WANs may be connected using fibre or copper telephone lines , satellite links , or radio links
• The Internet is the biggest WAN
• What are the factors that affect the Performance of Networks?

  • Bandwidth  
  • Available bandwidth being shared between too many devices on a network  
  • Connections and cables  
  • Signal quality and range affecting wireless performance  
  • Choice of hardware and network topology used 
• Bandwidth is the amount of data that can be transferred in a given time
• The greater the bandwidth , the better the network can perform (In other words, more data transferred = better network performance)
• Available bandwidth is shared between the devices on a network - too many devices or heavy use (e.g. streaming video) may cause congestion and slow the network
• To stop congestion or the slowing of a network, you can limit the bandwidth available to individual users
• Wired connections are generally faster and more reliable than wireless connections
• Fibre optic cables an give much better performance than copper cables
• Wireless performance depends on signal quality so is affected by:


  • The range of the device  
  • The amount of interference from other wireless networks  
  • Physical obstructions (like thick walls in buildings) 
• Choice of hardware (other than cables and network topology) affect the performance of networks