Network

• Advantages of a network

  • Ability to share software
  • Ability to share hardware
  • Ability to share data/files
  • Can access data from any connected computer
• Disadvantages of a network

  • Hackers can get into the network
  • Initial cost of the servers are very expensive
  • If the network goes down, everyone will be affected
• A network topology is an arrangement of links and nodes on a network
• Bus topology

  • Nodes are connected via a single cable/backbone
  • Messages are sent to all nodes across the backbone
• Advantages of Bus topology

  • It is cheaper because it requires less cabling
  • Quick to implement
  • It is easier to add more nodes to the network
• Disadvantages of bus topology

  • If the backbone fails, the entire network goes down
  • Difficult to trouble shoot
  • Data collisions happen often which causes the network to slow down
• Ring topology


  Data travels around the ring in one direction
• Advantages of ring topology

  • Prevents data collisions
  • Data is quickly transferred without a bottleneck
  • Additional nodes has little affect on bandwith
• Disadvantages of Bus topology

  • Difficult to troubleshoot
  • If the main cable goes down, the entire network is affected
  • Because all nodes are wired together, adding additional nodes causes the network to temporarily shut down
• Star topology

  • All nodes connect via a central node
  • It is the most common network topology
• Advantages of star topology

  • Better security
  • Easy to set up
  • Minimal network collisions
• Disadvantages of star topology

  • Expensive to install
  • Expensive to maintain
• Network devices

  • Switch: Looks at each packet of data and sends it to the computer it was intended for
  • Router: Stores the addresses of computers on the network
  • Bridge: It is used to link the network between buildings
  • Hub: A hub broadcasts data to all devices on a network.
• Standards are a set of hardware and software specification that allow manufacturers to produce goods and services that are compatible with each-other.
• The need for standards

  • Consumers are not forced to one vendor as there are no monopolies
  • ensures that hardware and software that are produced by manufacturers are compatible with each-other
  • They allow for communication between different networked devices
  • It is impossible to create networks that communicate without standards
• A protocol is a set of rules for data communication
• HTTP: Hypertext Transfer Protocol is used to transfer multimedia webpages over the network
• FTP: File transfer protocol allows the transfer of larger files across the network
• Simple mail transfer protocol (SMTP) allows the transfer of emails over a network.
• Internet message access protocol (IMAP) allows the transfer of emails from different computer systems via the internet.
• User datagram protocol (UDP) is an alternative to TCP but has no error checking or data recovery services.
• Dynamic Host control protocol: (DHCP) assigns dynamic ip addresses to devices on a network.
• Transmission control protocol (TCP) breaks data into packets to be sent over a network where IP rearranges the data as it was.
• Handshaking is when a computer system establishes a devices readiness to communicate.
• The internet is a network of networks that uses TCP/IP to link devices
• Circuit switching involves creating an end to end communication for the transfer of data.
• Data packets often contains

  • Checksum
  • Destination IP address
  • Source IP address
  • sequence number
  • Re-assembly information