Networks

Networks

1. Packets

   • Collection of data transmitted over a network
   • Data may split up into many packets to take different routes

2. Protocol

   • A set of rules in an agreed upon format to allow device communication
     • I.e. type of error check ,compression method, recieved message and sent message indication
   • TCP/IP
     • Transmission control protocol/internet protocol Ip sets out the format and adress pf pakets and TCP allows the sending and recieving of packets
   • HTTP
     • Hypertext Transfer Protocol used to transfer multimedia web pages over the internet
   • FTP
     • File transfer protocol used of copying and pasting files over a network (large files)

3. Number of computer systems connected together

   • Share hardware, software, data and files
     • Easy internal communication (e-mail)
       • Easy security and activity monitering
   • Hackers and security problems
     • All computers effected if server is down
       • expensive - network manager and initial costs

4. WAN (Wide area network)

   • Computers can connect over large distance (different buildings and countries)
   • Eg. Internet

5. LAN (Local are network)

   • All computes located relatively closley such as the same building

6. Bus Topology

   • Each node/ computer system os connected to a single cable with terminators at each end
     • Easy to impliment and add new computers
       • Quick to set up
         • Not many cables so cost effective
     • Limited cable length and station amount
       • Main cable problem shuts down network
         • Low security
           • Likely collisions

7. Ring topology

   • each computer connected to two other forming a ring
     • Constant data transfer speeds
       • Little network collisions
         • additional nodes has little bandwidth impact
           • simple transmission - one direction
     • one computer fail effects all others
       • cable problem shuts down network
         • difficult troubleshooting
           • hard to add new nodes

8. Star Topology

   • Each computer connected to central node called the hub
     • Fast network speed
       • Easy set up and adding nodes
         • failures have little effect on other nodes
           • Minimal collisions
             • Better Security
     • Expensive to install
       • hub required
         • if hub goes down whole network crashes

9. Security

   • User access levels
     • not all users should have full data access allow certain users read and/or write access
   • Suitable passwords
     • Complex passwords
       • Upper and lower case
         • PasSWOrd
       • alphanumeric characters
         • Pa55word1234
       • non alphabetic and alphabetic characters
         • P@ssw*rd!
     • Attempts = Number of characters ^ Password length
   • Encryption techniques
     • Conversion of data using an algorithm into cypertext
       • Needs description key
         • Ie - XOR logical operator

10. Network policies

    • Acceptable use
      • documents outlining rules users are required to follow
    • Disaster recovery
      • Before disaster
        • make backups
          • preventive measures & training
            • Risk analysis
      • During disaster
        • Staff Response
          • Contingency plans
      • After disaster
        • Recovery measures
          • Reinstall software
            • Replace hardware
    • Backup
      • Copy data so it can be restored if original data is lost
        • Needs to be updated constantly
      • 3 Different backups in
        • Grandfather-farther-son method
    • Archiving
      • storing no longer current or frequently used data

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