1.3 Computer networks, connections and protocols Flashcards
Local Area Network (LAN)
- Covers small geographical areas at single sites
- Hardware is usually owned by the organisation using it
- Can be wired on wireless
What can users on a LAN do?
- Access and share files on the network
- Share hardware
- Share an internet connection
- Log in from any device on the network
- Roll out security and software updates to all computers at once
Wide Area Network (WAN)
- Connect LANs in different geographical locations
- Organisations hire infrastructure (e.g. fibre optic lines or satellite links) from telecommunications companies who own and manage the WAN
- More expensive to set up than LANs
5 factors affecting network performance
- Bandwidth
- Number of users
- Transmission media
- Error rate
- Latency
Bandwidth
The amount of data that can be sent and received successfully in a specified period of time
Number of users
Too many users or devices on the same network can cause it to slow down if there is insufficient bandwidth available
Transmission media
- Either wired or wireless
- The type of cable used to transfer data, e.g. Fibre optic cable offers higher bandwidth than copper cables
Error rate
- When the transmission of data fails and it has to be sent again until it arrives correctly
- Quality of signal may depend on the distance if it is wireless, or the quality of the material used
Latency
- Delay between sending and receiving data
- Affected by the number of devices on the network and the type of connection device
Five pieces of network hardware
- Network Interface Controller (NIC)
- Switch
- Transmission media
- Wireless Access Point (WAP)
- Router
Network interface controller (NIC)
Allows devices to connect to a network -> usually built into the motherboard
Switch
Receives and transmits data between devices on a LAN using MAC addresses
Transmission media
Wires or wireless radio waves that allow data transmission between devices
Wireless Access Point (WAP)
Allows devices to connect to a network wirelessly. Similar to a switch
Router
Transmits data between networks by directing data as ‘packets’ to their destination
Wired networks
Tend to be faster and more reliable than wireless networks. Three cables to connect devices on an Ethernet (wired) network:
- Unshielded twisted pair (UTP)
- Coaxial
- Fibre optic
Unshielded Twisted Pair (UTP)
Copper wires twisted together in pairs to reduce internal interference
Coaxial
A single copper wire surrounded by plastic insulation and metallic mesh to shield from outside interference
Fibre optic
Transmits data as light. Can send data over long distances with little interference. High performance but expensive
Wireless Networks
Radio waves transmit data between devices on wireless networks. They tend to be cheaper and more convenient than wire networks.
Two common wireless technologies:
- Bluetooth
- Wi-Fi
Bluetooth
- Direct connection between two devices to share data
- Low bandwidth
- Max range -> 10 metres
Wi-Fi
- Can connect multiple devices to a LAN at once
- High bandwidth
- Max range -> 40-100 metres
Client-Server Networks
Files, software, user profiles and passwords are all stored centrally on the server.
Client sends a request to the server. Server processes the request and responds
Pros of Client-Server Networks
- Easy file tracking -> all stored centrally
- Back up files and update software easily
- Servers are reliable and always on
- Security -> Servers can request passwords or access levels before fulfilling requests