3.1 Networks and topologies Flashcards
Network
A network is two or more devices connected together with the purpose of sharing resources.
Advantages and disadvantages of networks
Advantages - Users can share resources such as printers and connections to the internet.
Users can access their files from any computer on the network.
Communication can be made easier via email and social networks.
Users can share files and folders such as central databases and spreadsheets.
Servers can be used to provide centralised backups, updates and security.
Disadvantages - There are increased security risks to data.
Malicious software can infiltrate the network and render it unusable.
Servers and switches can provide a central point of failure, resulting in users not being able to complete tasks using their computer.
Factors can impact the performance of the network such as the number of users and data on the network at one time.
Local area network (LAN)
A local area network is a network which has a small geographical area. All of the hardware is owned by the company / organisation / household.
LANs use unshielded twisted cables, fibre optic cables or wireless connections (Wi-Fi).
Wide are network (WAN)
A wide area network is a network which has a large geographical area. They are a connection of LANs joined together. Computers on a WAN are connected via routers. The hardware used to connect the networks together are not all owned by the same company / organisation / household for example telephone lines. WANs use fibre optic cables, telephone lines and satellite to connect the LANs together.
Factors of network performance
Number of users - This is how many users are on the network at the same time. Too many users can cause the network to slow down if there is not enough bandwidth for all of the data being sent and received.
Bandwidth - Bandwidth is the amount of data that can be sent and received at any given time. it is measured in bits per second. a smaller bandwidth means less data can be sent and the network can slow down, potentially to the point of becoming unusable.
Latency - Latency is the delay between data being sent and received. If there is a big delay between the two, more data will be on the network causing collisions. This can lead to even more packets of data being sent as the error rate has increased.
Error rate - Error rate is the measure of how many packets of data do not reach their destination. An increased error rate occurs in less reliable connections - a poor wireless signal would be a contributing factor to an increased error rate.
Transmission media - Transmission media is the type of cable used in wired connections. Wired connections offer a higher bandwidth than wireless connections. The main option for transmission media are unshielded twisted pair and fibre optic. Fibre optic has a higher bandwidth than copper cabling as well as faster transfer speeds.
Local area network hardware
Network hardware is a selection of essential components that enable the connectivity and communication of devices within computer networks.
Router, Wireless access point (WAP), Switch, Network interface card (NIC) and Transmission media.
Router
The router is responsible for routing data packets between different networks. The router connects networks together. The router can manage and prioritise data traffic, which can help to keep connections stable. The router will assign IP addresses to the devices on the network.
Wireless access point (WAP)
The wireless access point allows wireless devices to connect to a local area network. The WAP connects to a switch or hub via an ethernet cable. The WAP range is limited so the use of multiple WAPs can be used for complete coverage.
Switch
A switch allows multiple wired devices to connect to a local area network. The switch is an active device, which means it can inspect network data and route it to the correct devices, thus reducing traffic on the network. A switch can contain extra software to allow administration and configuration.
Network interface card (NIC)
An NIC is required to access a network providing a unique MAC address which is used to send data packets to and from a computer.
The NIC connects the computer to the transmission media / Wi-Fi / Ethernet cable.
Transmission media
Transmission media is the phrase used to describe the method of connecting a wired network.
Unshielded twisted pair (UTP), Coaxial (copper) and fibre optic.
Unshielded twisted pair (UTP)
A twisted pair cable is made up of insulated pairs of copper wires twisted around each other. Twister pair is low bandwidth and more affordable than the other two cables, so it is commonly found in local area networks.
Coaxial
A coaxial cable (uses electricity) is medium bandwidth and more expensive than UTP. Coaxial cables are used to connect large scale networks such as telephone networks and digital cable / satellite television.
Fibre optic
A fibre optic cable (uses light) unlike the other two, is unaffected by electrical noise making it the fastest in terms of data transfer. Fibre optic is high bandwidth and the most expensive. It is commonly used for high data volume networks and long distance connections such as between cities and countries.
Internet
The internet is a collection of networks spanning the whole world. The internet is the largest wide area network. The internet is used to provide connectivity and is different from the World wide web, which is a collection of web pages you access via a web browser.
