Networks & Topologies

• Network


  Two or more devices connected together to share resources
• Local Area Network (LAN)


  A network within a small geographical area, usually under 1 mile
• Wide Area Network (WAN)


  A network spanning a large geographical area, made up of connected LANs and uses external hardware such as satellites and telephone lines
• Advantages of having a network


  • Users can share resources like printers and internet connection, and users can access files and communicate easily from any computer on the network
• Disadvantages of having a network


  • There is an increased security risk to data from malware or hackers
• A WAN connects networks over a large geographical area spanning miles
• Networking hardware used in WANs


  • Routers, telephone lines, fiber optic cables, and satellites
• Bandwidth


  The amount of data that can be transmitted per second, measured in bits per second
• Latency


  The delay between data being sent and received
• Error rate


  The measure of how many data packets do not reach their destination
• Transmission media


  The cable type used for wired network connections
• More users reduce the available bandwidth per user, potentially slowing the network
• Fibre optic cables have the highest bandwidth compared to copper cabling
• An increased error rate occurs with less reliable connections like poor wireless signals
• If the maximum bandwidth is used, devices cannot transmit data until bandwidth frees up
• Using higher bandwidth or more reliable transmission media can decrease latency
• Peer-to-peer model


  All computers are equal peers with no dedicated servers, each computer is responsible for managing its backups, security and connections
• Disadvantages of a client-server network


  • Servers are expensive to purchase and maintain, and require specialist IT staff
• If the central server fails, all client machines lose access to network services
• Role of a router


  Routes data between different networks like a LAN and the internet (WAN)
• Switch


  Connects multiple wired devices to a LAN and routes data between them
• Transmission media


  The cables used for wired network connections
• Main transmission media types


  • Unshielded twisted pair (UTP), Coaxial cable (copper), Fibre optic cable
• Fibre optic cables are unaffected by electrical noise
• Switches are active devices that inspect network data to route it efficiently
• Internet


  A massive collection of interconnected networks spanning the world
• Difference between Internet and World Wide Web

  The Internet provides connectivity, while the World Wide Web is the collection of web pages accessed via browsers
• Domain Name System (DNS)

  Translates human-readable domain names (web address) to IP addresses for connecting to web servers
• Cloud computing


  Uses remote servers on the internet to store data and run applications
• Cloud data can be accessed anytime from any internet-connected device which has the login credentials
• Expanding the capacity of cloud storage can become expensive if using it across a business
• Network topology


  The physical structure of the network, defining how the network hardware will be arranged
• All devices connect to a central switch in a star network topology
• If any single cable stops working in a star topology, the rest of the network will continue to work
• Disadvantage of a star topology

  • The central switch is a single point of failure
• Mesh topology


  Allows all computers to be connected to all other computers, known as a full mesh network topology
• Devices like smart thermostats, security cameras, and smart light bulbs often form a mesh network to communicate with each other and a central hub
• Disadvantage of a full mesh topology

  • Increased complexity and cost of the setup and maintenance due to the numerous interconnections between devices