Networks

Networks

1. Hardwares

   • switches
     • receives data from devices
     • transmits data
     • uses MAC addressing
   • Network Interface Controller
     • NIC
     • built into motherboard
     • exists for both wired and wireless
   • Routers
     • responsible for transmitting data between networks
     • crucial role on the Internet
     • directs data called packets
     • connects LAN's to internet

2. Types of Networks

   • LAN
     • Local Area Network
     • covers a small geographical area
       • on a single site
     • are either wireless or wired
     • found in businesses, schools and universities
     • why use a LAN?
       • sharing files is easier
       • can share the same hardware, eg. printer
       • can share Internet connection
       • can communicate cheaply and easily
       • user accounts can be stored centrally
   • WAN
     • Wide Area Network
     • connects LAN's that are in a different geographical locations
     • organisations hire infrastructure
       • much more expensive
     • connected using fibre or copper
       • telephone lines
       • satellite links
       • radio links
     • internet is a big WAN

3. Factors that affect networks

   • Bandwidth
     • amount of data transferred in a give time
     • too many devices can cause congestion
     • greater bandwidth, better the performance
   • fibre optic cables
     • faster
     • reliable
     • better than copper cables
   • choice of hardware
   • network topology
   • wireless depend on signal quality
     • affected by range
     • affected by physical obstructions

4. Client server

   • managed by server
   • files and software stored centrally
   • clients send requests to server
     • server processes the request
     • the server responds
     • client-server relationship
   • server stores
     • user profiles
     • passwords
     • access info
   • pros
     • easier to keep track of files
     • easier to perform back-ups
     • easier to install and update software
     • easier to manage network security
     • servers are reliable and are always on
   • cons
     • expensive
     • require an IT expert to maintain
     • server dependant
       • if server goes down, clients loose access
     • server may become overloaded

5. Peer-to-Peer

   • all devices are equal
   • store files individually
   • connect directly to eachother
   • no server
   • pros
     • easy to maintain
     • no dependance
   • cons
     • no centralised management
     • less reliable
     • machine are prone to slow down
     • copying files between devices duplicate them
       • easy to loose track

6. Topology

   • star
     • connected to a central switch or server
       • allows many devices to access the server
     • pros
       • simple to add more devices
       • good performance
       • if a device fails, the rest of network is unaffected
     • cons
       • if wired, cables are expensive
       • problem with switch, whole network is affected
   • mesh
     • connected directly or indirectly
     • no central server
     • data sent along fasted route
     • pro
       • no single point where the network can fail