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1.3.1 Networks and topologies - Coggle Diagram
1.3.1 Networks and topologies
Types of networks
LAN
Two or more network-enabled devices connected within a fairly close geographical area
Advantages
Resources and files can be shared by users, this means that they can collaborate on a project
Backups of files and documents can be done centrally rather than needing to do it from each machine
A user can log on from any workstation and still access all of their files
An anti-virus and malware check can be carried out from the server to all workstations
Data can be transmitted very quickly between networked computers
A LAN at home allows many devices to connect to one another
Disadvantages
Network failure
Expert support is required
Slow service
Viruses and malware spread
Expensive
Security
WAN
Connects two or more local area networks (LAN) that are in different geographical locations
Disadvantages
Can be expensive to hire a WAN service
Owned by a number of external suppliers and so a failure of the WAN is usually beyond the control of the company to fix.
Advantages
Allows workers to collaborate over a wide area, even across continents
Allows files and data to be shared between LANs
Allows LANs to connect to one another
Connections
Peer-to-peer
Needs little technical skills due to built-in support
Files and data are stored locally or in a shared folder hosted by a specific peer computer
Each peer can be set to share folders
A broken or disconnected peer computer has an effect on all peers
Each peer may have its own local user accounts
Commonly used in small LANs such as at home or a small office with few computers
There is no central server
Can use a standard operating system
Client-server
One or more servers
A workstation computer or 'client' is used to log in to the server
The network administrator sets up shared folders on the server
Needs technical skill to maintain a client-server network
Files and data are stored centrally on the server
A broken workstation has no effect on the overall network
A broken server takes down the entire network
Commonly used in organisations that need to connect many workstations / computers together
Requires a network operating system
Network hardware
Switches
A high-speed device that receives incoming data packets and redirects them to their destination
Network Interface Card
An electronic chip built into the motherboard of the device
Routers
A device that transfers data packets, by the most efficient route, from one network to another
Transmission media
Ethernet cables
Made up of a set of four 'twisted pair' copper wires enclosed in a plastic sleeve with a standard network plug on the end. Data is carried through the cables by means of electrical signals
Made up of many glass fibres held together inside a sheath. They use light signals to transport the data
Wireless access point
A hardware device or configured node on a local area network (LAN) that allows wireless capable devices
Hub
A piece of hardware used to connect computers on the same network together
Types of networks
Bandwidth
How much data can be moved across a network in a given time
kilobits=a thousand bits
megabits=a million bits
gigabits=a thousand million
WiFi performance
Radio interference
Limited connections
Range
Performance of wired networks
Number of users
Error rates
Bandwidth available
Latency
Type of cable connection
Performance of wireless networks
Range from WAP
Radio interference
Number of connections available
Physical layout
Network topology
Star
A central device directly connected to all other nodes
Advantages
Reliable
Simple to add or remove a node as it has no effect on any other node
Good security
Very few data collisions as each node has its own cable to the server
Disadvantages
Extra hardware such as hubs and switches may be needed
Installing the network usually needs experts to set it up
The most expensive network layout to install because of the amount of cables needed
If the central switch or server fails, the whole network is down
Requires a high performance switch or server in the centre as all traffic passes through it
Mesh
Advantages
Excellent for wireless networks as each node re-broadcasts all the data packets it receives
It can handle very high data traffic rates
There is no central node to fail
Data packets can be sent simultaneously
Very robust
Devices can join or leave the network without affecting the overall network
Each node relays the data it receives to other nodes within reach
Disadvantages
Rapidly becomes an impractical topology for wired network as so many cables would be needed
Very expensive for a wired network due to cabling and switches needed
The number of connections increase massively as more nodes are added
Needs complex co-ordination to be effective