Computer Networks GapFill

A computer network is defined as two or more  laptopscomputers or devicesphonesprinters which are linked together, either through the use of physical cables or wirelessly. The main types are Wide Area Networks, (WAN),  Local Area Networkslesser networklimited networkleased network (LAN) and Personal Area Networks (PAN). In addition to computers and printers other devices such as tablets, games consoles, mobile phones and a range of smart devices like fitness trackers, TVs, remote doorbells etc.

The key advantages of networks are the ability to   process datasend datashare data and peripheralsmanipulate data, in addition to sharing one  scannerphotocopierprinterInternet connection. In large organisations, like schools or businesses networks specialist network software is used to centrally manage users’  access rights and securitynumbersnamessignatures, including data backup, firewalls and anti- malware software. A computer networks also allow users to log on to any computer in the network and get access to their own files meaning that people can work in a variety of locations.

Networks also have disadvantages, if the main file server in a network stops working no-one can access any files. Larger networks also need additional hardware which can be costly; these more complex systems will need a network manager to maintain them and ensure that all security features are kept up-to-date. For example, if anti- malware software is not updated, malware will spread very quickly across all the computers in the network.

A WAN covers a  area about 5 mile diameterarea set by the network managerarea about a mile diameterwide geographical area, which may be world-wide, which connects together the individual LANs at each separate site. These are used by large global organisations such as banks and use a range of methods to communicate between the sites which may include  WiFicablesatellitetelephone, cables and telephone lines which will commonly be leased or hired from telecommunication businesses.

Local Area Networks cover a much smaller area, such as a school, college or hospital and will use a combination of  linkswireswired and wireless connectionscables. The smallest networks are PAN’s, these connect devices over the shortest distances, a few metres at most and use  Bluetooth technologyTCPMACWAN to link personal devices like wireless headphones to a mobile phone.

Networks can be connected in a number of topologies with their own benefits and limitations. Examples of topologies include star networks, which connect devices   to two other devices each to form a loopwith a central switchdirectly to one anotheralong a single central network, and bus networks in which devices are connected   to a single cable known as a backbonea networkdirectly to each otherin a loopwith a terminator at each end. Star networks are more complex to set up and need more cables than bus networks however they avoid the problem of  data collisionswrong protocolno protocolold protocol as the data is sent directly from the main switch to the intended computer; bus networks are simpler to set up and use less cable but all data is sent along the backbone to all nodes on the cable so if the central cable fails the whole network is useless. In a star network, a cable failure affecting just one workstation on the network will not stop it functioning but a failure of the central switch or file server would.

Networks make use of many different types of hardware to connect devices, including routers, switches, NICs and WAPs. Routers send  between a client and a serverwirelesslybetween networksbetween two clients; switches connect devices on a single network and identify where to send data by using the   IP addressesMAC addressesWANsdomain names of the connected devices; NICs allow devices to   make wired connectionsmake wireless connectionsencrypt dataconnect to networks and a WAP allows devices to connect to the network   over very long distanceswirelesslyquicklysecurely.

A  MACprotocolPANconnectionis a set of rules which all device manufacturers use which control how networks and devices communicate with each other so that   all data is encryptedevery device can understand the signals being sent by other devicesno data is corrupteddata transfer speeds can be increased. Networks use a number of different protocols. The protocols used over the Internet are split across four layers: the   transportnetworkapplicationlink layer, which ensures that data can be understood by the application being used; the   networkapplicationlinktransport layer, which establishes connections by defining the length of data signals, etc.; the   applicationtransportnetworklink layer, which deals with routing data from the sender to the receiver; and the   applicationvirtualtransportlink layer, which handles the physical properties of transmission signals.

Ethernet and Wi-Fi are two sets of protocols that determine how data is transmitted across a network. In wired Ethernet networks, if two signals are sent along the same wire at the same time, the signals collide and so both signals are corrupted and must be resent. Wi-Fi networks limit interference between signals by splitting the available network frequencies into overlapping channels, although signals on a channel can cause interference with any channels that it overlaps. Wi-Fi networks can use a 5GHz or a 2.5GHz frequency channel. A 5GHz network has   fewer non-overlapping channelsmore wired connectionsmore non-overlapping channelsfewer wired connections that can be used simultaneously without causing interference,   but can only send data in one directionbut has a shorter rangebut requires line-of-sight to connected deviceshas a longer range and is less able to go through walls.