Unit 1.3 Networks Flashcards
Types of networks
LAN
WAN
What is a Local Area Network (LAN)
A Local Area Network covers a small geographical area located on a single site
What is all the hardware for a LAN owned by
All the hardware for a LAN is owned by the organisation using it
How are LANs wired
LANs are wired with UTP cable, fibre optic or wireless using Wi-Fi
What is a Wide Area Netowork
A Wide Area Network covers a large geographical area, connecting LANs together.
The infrastructure between LANs is leased from what?
The infrastructure between the LANs is leased from telecommunication companies who own and manage it.
How are WANs connected
WANs are connected with telephone lines, fibre optics cables or satellite links
Advantages of networking
Users can share files
Users can share peripherals: printers and connections to other networks, e.g. The Internet
Users can access their files from any computer on the network
Servers can control security, software updates and the backup of data.
Communication with other people, e.g. email and social networking
Disadvantages of networking
Increased security risks to data (as it is now shared)
Malware and viruses can spread very easily between computers (connected devices)
If a (central)server fails, the computers connected to it may not work (depending on the configuration)
The computers may run more slowly if there is a lot of data travelling on the network (and a lot of traffic on the network)
How are computers in a LAN connected
Computers in a Local Area Network (LAN) are connected with a switch
How are computers in a Wide Area Network connected
Computers in Wide Area Networks (WANs) are connected with a router
Factors that affect the performance of networks
Number of devices connected
Bandwidth
Transmission media
Latency/hardware limitations
Amount of traffic on the network
(Error rate)
What is bandwidth
The maximum amount of data that can be sent and received successfully in a given time
This is not a measure of how fast data travels, but how much data can be sent on the transmission media.
_______
e.g. water travelling through a straw and a drain pipe.
Water can travel at the same speed, through both, but bandwidth is much lower when water travels through the straw than drain pipe.
What is bandwidth measured in
Measured in bits per second, often called bit rate.
Explain how bandwidth affects the performance of networks
The greater the bandwidth, the more data can flow, even if data is travelling at the same speed
Explain how the number of users affect the performance of networks
All the devices are sharing the available bandwidth
As more devices join the network, the bandwidth is divided into smaller and smaller amounts
Explain how the type of transmission media affects the performance of networks
Wired connections are usually a lot faster than wireless connections with fibre optic being a lot faster than copper cable
Explain how the amount of traffic on the network affects the performance of the network
The more traffic, the more collisions there will be between the data packets (a small block of data that is transmitted from one computer to another) being transmitted.
This leads to transmission errors and the packets having to be resent
Explain how latency/hardware limitations affects performance of a network
Too much traffic may be routed through a single point leading to congestion and bottlenecks.
More switches and routers can be added to help improve the performance
Explain how type of network media affects performance of a network
Wired connections are usually a lot faster than wireless connections with fibre optic being a lot faster than copper cable
Describe the client-server network
A server controls access and security to one shared file store
A server manages: access to the internet, printing jobs, it provides email services and runs a back up of data
A client (individual clients connected to the server) makes requests to the server for data and connections
Advantages client server network
Easier to manage security files (easier to manage the security of the files on this network)
Easier to take backups of all shared data.
Easier to install software updates to all computers (easier to install software updates across the network)
Disadvantages client server network
Can be expensive to setup and maintain
Requires IT specialists to maintain
The server is a single point of failure
Users will lose access if the server fails
Describe the peer to peer networks
A peer is a computer on a network, and is equal to all other peers
Peers serve their own files to each other
Each peer is responsible for its own security
Each peer is responsible for its own backup
Peers usually have their own printers
You can send print jobs to another per to process, but that peer would need to be switched on to be able to communicated with the connected printer
Advantages of peer to peer network
Very easy to maintain
Specialist staff are not required
No dependency on a single computer
Cheaper to set up
No expensive hardware required
Disadvantages to peer to peer networks
The network is less secure
Users will need to manage their own backups
Can be difficult to maintain a well ordered file store.
What is a network interface card/controller
A network interface controller (NIC) connects a device to wired or wireless networking connection
How do NICs work
They use a protocol ( a set of rules that governs how communication between the device and the connected media or wireless should occur) to determine how the connection should work (+ to ensure successful communication)
They allow (connect) a device to connect to either a wired or wireless network
What is a wireless access point
Allows wireless enabled devices to connect to a network without cables
Advantages of wireless access point
More convenient
Wireless connections are popular because it avoids the need to install cables
Disadvantages of wireless access point
They have less bandwidth than a wired connection (Bandwidth on a wireless connection is lower than on a wired connection)
Security is more of a concern with wireless connections
Connection is sometimes not as strong or reliable as wired connections.
What is a switch
Sends data between computers on a LAN
How do switches work
They segment the network by forwarding traffic to the correct location (to the correct device on another switch)
Switches learn which devices are connected and understand how to forward traffic in an intelligent way.
Switches use the network interface controller address on a device to route traffic
They learn where devices are on the network by reading the ‘from address’ on each packet that they receive.
If they recognise the ‘to address’, they can route data packets to the correct connection
If not, they will broadcast the packets to all connections.
What is a router
Sends data between networks
Features of a router
It creates a WAN from a number of LANs
You cannot connect to a WAN (such as: The Internet) without using a router
A router is needed to connect a Local Area Network to a Wide Area Network.
A router uses an IP address (Internet Protocol address) to route traffic to other routers
Types of transmission media
Fibre optic cables
Copper cables (UTP)
Advantages of copper cable
Copper cable is cheap and flexible which makes it easy to install
Wired connections assure maximum bandwidth, security and reliability
The wired connections are made up of twisted pair cables, the wires are twisted around each other to reduce interference
Normally a set of wires for transmission and a set of wires for receiving data.
The grade of copper and insulating material affects the overall cable and therefore the bandwidth.
Connections between desktop computers and a switch or router are usually achieved with a wired connection.
Advantages of fibre optic tables
Uses light to transmit data
Can cover much longer distances and greater bandwidth than copper – due to reduced interference
(They are therefore used in high-traffic connections such as between switches and to remote buildings)
Longer distance cables and wide area networks are usually connected with fibre optic cable
The backbone of The Internet uses fibre optic cables
Fibre optic has a higher bandwidth than copper and suffers from less interference.
