Network

Network

1. LAN and WAN

   • LAN is Local Area Network. This is contained within a small geographical area
   • WAN is Wide Area Network. This is not limited by geographical area
   • Advantages and Disadvantages
     • The wide area of WAN allows businesses to connect to the one network even if they are very far apart
     • They both share software and resources with connecting workstations
     • Messages can be sent quickly to others in the network
     • WAN can share information over a large area
     • LAN is cheaper than WAN and users can access the same files

2. Topologies

   • Bus Topology
     • A single cable is used to connect all the workstations and other devices
     • The cable can be a good thing because it is easy to find the error if there is one
     • The cable can be bad if it is damaged it will result in a catastrophic failure and it increases the chance of collisions
     • The Bus Topology is very cheap and it is easy to set up
   • Ring Topology
     • This is where each computer is connected to two other computers in a ring formation
     • Each computer receives signals from one of its connected computers
     • The data travels round the ring until it reaches its desired location
     • If any wire is damaged it will cause a catastrophic failure due to the data being unable to travel round the ring.
     • The Ring Topology does prevent any collisions though, due to its formation
   • Star Topology
     • This is where each workstation or device is connected to a central hub or switch
     • A hub sends each message to all other computers, but a switch checks the address, only sending it to the correct one.
     • This topology means that if one wire breaks, it is just that one device that is broken, not everything.
     • If the hub or switch break, it will result in a catastrophic failure
   • Mesh Topology
     • This is where each computer is connected to one or more other computers
     • A full mesh is where each computer is connected to the other. A partial mesh is where some computers are connected to the others
     • This topology prevents any catastrophic failures as if any wire is broken there are more wires that the data can travel through
     • Switching
       • Circuit Switching
         • This is where a path across the network is established for the data to travel through
         • That path is locked and it remains locked for the duration of the communication
         • Data is received in the same order it was sent and it arrives at a consistent speed. You can also read the transmission as soon as the first bit arrives.
         • However, you can only send one transmission at a time or you will clog the network
       • Packet Switching
         • This is where the data is split into small chunks called packets
         • Each packet is sent individually, likely using different paths
         • The packets are re-assembled at the other side
         • Multiple transmissions can happen simultaneously and large transmissions don't clog up the network
         • Lag is needed to allow several packets to arrive before reading, as the first packet sent may not be the first packet received