Networks

An arrangement of two or more computing devices (nodes) connected together in order to communicate with each other and share resources

• To share data and software / share hardware peripherals (printers, hard drives, etc.) / share internet connections and services • To support collaborative working / provide centralised support and backup services • To enable rapid employment of new software and updates / enable people to communicate with each other using services (e.g. email)

• PAN - personal area network • LAN - local area network • WAN - wide area network

A network within the range of an individual person

• A network in a small area (e.g. a home, school, office building) or group of buildings on a site, existing within a small geographical area • Usually managed by local manager or team at site

• A network that connects separate LANs over a large geographical area • Large companies connect LANs at different sites to share data and resources • Managed by several different people or parts of an organisation working together / each LAN could be managed independently

• Client-server • Peer-to-peer

• A network containing a server that can back up and store data centrally • All other devices each considered a ‘client’, may be more than one server

• A network configuration containing no central server • Each device equal in responsibility, each with the ability to work as a client and a server

• Wired (e.g. via cables) • Wireless

The distance over which data can be transferred

The capacity at which a network can transmit data

The delay in time between data being transferred and the instruction which caused the transfer

• Made of thin copper strands, transmits data as electrical signals • High noise contamination • Prone to external interference • Low bandwidth • Easy installation / fairly cheap installation

• Very low noise contamination • Not affected by magnetic interference - data carried using beams of light • Secure/reliable data transmission • Much higher bandwidth over a longer distance • Difficult installation/maintenance • Expensive due to cost of electrical components - although does not corrode • Made of glass so more fragile

• Wi-Fi • Bluetooth • Zigbee • RFID • NFC

• Difficult installation - Each device needs own dedicated cable • Limited flexibility - Number and location of cable connections is fixed, making changes once set up is likely to disrupt LAN • Long range • High bandwidth • Low latency - Cables have protective coverings, less susceptible to interference • Good security - Impossible to tap into physical cables without being in same location as cable

• Easy installation - Adding new devices easy, only WAPs to be connected by cable • Versatile - Devices can be moved around without losing connection, new users added easily • Short range - Walls and other physical obstacles may obstruct signal • Low bandwidth - All active devices must share available bandwidth • High latency - Susceptible to interference from other wireless networks or devices • Poor security - Anyone within range can intercept transmissions

The rate at which data is transferred within a network

Bits per second, bps (e.g. Mbps, Gbps)

Data transfer rate (bps) = File size (bits) ÷ Time (s)

The way in which devices on a network are physically arranged and connected together

• Bus • Star • Ring • Mesh