LAN and Topologies

• LAN


  Local Area Network; connects nearby computers such as in a school, business, home
• School Network


  • Contains many computers
  • May include desktop computers, laptops and other devices such as tablets and smartphones
• How does the school connect all these devices together?

  Connect devices using a LAN
• LAN


  Local Area Network; operates on a single site such as a school, hotel or business using their own cabling systems
• Difference between LAN and WAN

  • LANs are local and located within one location such as a building
  • WANs connect networks at remote locations via leased lines
• Connecting computers in a LAN

  Advantages and disadvantages compared to leaving the computers as standalone machines
• Network Topology


  The way in which parts of a system are connected
• Network Topologies


  • Star
  • Mesh
• Star Topology


  • Computers and other devices (known as nodes) are all connected to a central switch
• Full Mesh Network


  • Nodes act as routers for data in order to relay and propagate data in the network
• The Internet uses a partial mesh topology
• Mesh principles


  Affect wireless networks
• Wireless Mesh Networks


  • Only one node needs a wired Internet connection - no other cabling or infrastructure is required
  • The more nodes that use the network, the more routes there are for data to travel through
  • A node within broadcast distance of three other nodes, will have triple the standard bandwidth
  • As the distance between one node and another is halved, signal strength becomes four times stronger
• Network Hardware required to connect a stand-alone computer to a LAN

  • Network Interface Card/Controller (NIC)
  • Router or switch
  • Modem
  • Wireless Access Point
• Router


  Looks at the destination of packets of data and sends them to the network that is closer towards their destination
• Switch


  Connects each node (computer) in a network and knows the MAC address of all connected computers and devices
• Ethernet


  Family of standard local networking 'protocols' or rules that describe how devices should format data ready for transmission between computers on the same network
• Ethernet Protocols


  1. Nodes will wait until the connection is quiet before attempting to 'speak' or transmit

  2. Two nodes attempting to transmit simultaneously will stop and each wait a random period before reattempting
• Transmission Media


  The way that communication is sent through the network
• Types of Transmission Media

  • Ethernet cable
  • Fibre optic cable
  • Wi-Fi/wireless/microwaves
  • Coaxial cable
  • Copper cable