1/68
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Serial Data Transmission
Single bits are sent one after another along a single wire.
Parallel Data Transmission
Multiple bits are sent down several wires simultaneously.
What happens when data skew occurs?
bits sent together may not be received together
Bandwidth
the range of signal frequencies that may be transmitted.
Baud rate
The rate at which signals on a wire may change.
Bit rate
The number of bits transmitted per second.
Latency
Time delay between the moment something is initiated and the moment the effect begins
Crosstalk
unwanted transfer of signals between communication channels
Synchronous data transmission
a clock signal is used to time when signals are sent.
Asynchronous data transmission
sender and receiver have separate clocks which are not kept synchronised - a start bit is used to signal the arrival of data and to synchronise the transmitter and receiver temporarily
Advantages of a network (5)
Sharing resources such as printers makes it cheaper
site licenses are likely to be cheaper than several standalone
files can be shared easily
work can be easily accessed using any computer on the network
data is easy to backup as all the data is stored on the server
Disadvantages of a network (4)
Purchasing the network cabling and file servers can be expensive
Managing a large network is complicated - requires training and usually a network manager
if the file server breaks down the files on the file server become inaccessible
viruses can spread to other computers throughout a computer screen
Advantages of wired networks (4)
reliable
faster (than wireless)
more secure
can extend further easier
Disadvantages of wired networks (3)
can be expensive
less flexible (cannot easily move devices)
trip hazards
Advantages of wireless networks (3)
cheaper
very flexible
no trip hazards
Disadvantages of wireless networks
not always reliable
slower
less secure
donât extend very far
Where are Ethernet cables usually used for
You will usually find them in buildings - they connect the school computers together and are widely used in businesses
Where/What are fibre optic and copper cables used (for)
usually used to join together houses, businesses and other locations externally
What do copper cables use to work
electrical signals travelling along the wire (sometimes slow)
What do fibre optic cables use to work
Fibre optic cables use light to transmit data, and light moves at the speed of light! So these cables are a lot faster (than copper cables)
What does PAN, LAN and WAN stand for?
Personal area network
Local area network
Wide area network
LAN
when computers or devices are connected together over a single geographical area, such as within a home, a building or one site. (eg. the school/home)
WAN
when computers or devices are connected together over multiple geographical areas. (eg. the internet)
PAN
network on a very small scale. (eg. Bluetooth)
What are the 4 components that allow you to access the internet
The modem, the router, the switch, the WAP (Wireless access point)
What does the modem do?
Connects the device to the internet through a phone line
What does the router do?
A router is a networking device that forwards data packets between computer networks
What does the switch do?
Allows you to connect multiple devices to the router
What does the WAP do?
Lets your wireless devices connect to the network
Whats the purpose of a stop bit?
ensures that the receiver has time to process each byte before receiving the next one
Whats the purpose of a start bit?
temporarily synchronises the clocks in both the receiver and the transmitter
Advantages of a bus topology
Cheap as it uses the least amount of cable
Adding another computer is easily done
Disadvantages of a bus topology
Slow with many computers (has to check with every computer)
If the backbone breaks the whole system breaks
Advantages of a ring topology
Cheap to expand
Does not rely on a central hub
Disadvantages of a ring topolgy
slow if a lot of computers are on the system
If one computer breaks the whole network breaks
Advantages of a star topology
If a cable fails it only affects one computer
Computers can be easily added
Disadvantages of a star topology
more cabling needed
fail if the centre hub failsÂ
Topology definition
The structure of the connections that connect devices to the network.
Physical topology definition
The physical layout of the cabling between the devices on the network
Logical topology definition
How the data flows around a network
How does a logical bus topology work
The network will physically be set up in one way however it will logically operate like a bus topology. Using a bus protocol meaning it will check with each computer if the packet is meant for it like a bus topology
Client server definition
A system in which some computers (the clients), request services provided by other computers, the servers
Peer-to-peer network definition
A network that has no dedicated servers. All computers are of equal status and can both share resources themselves and use resources from other computers
Server definition
A computer that provides shared resources to network users
3 examples of servers
fie server
mail server
database server
3 examples where peer-to-peer networks are used
file sharing
online gaming
streaming media
3 examples where client servers are used
the internet
in businesses (file servers, database etc)
cloud services
What is Wi-Fi
A family of related protocols that define how devices should communicate over wireless connections (WLAN)
What does Wi-Fi allow you to do
Allows you to create a WLAN thats based on internation standards
What two (extra) components required for wireless networking (compared to wired)
wireless network adaptor
wireless access point
Whats a wireless network adaptor
a piece of hardware, such as a device or a card installed inside a computer, that allows a device to connect to a wireless network (like a Wi-Fi network) or the internet without using an Ethernet cable
What are the 3 ways to make wireless networks more secure
Disabling SSID broadcast - means that in order to connect to the network you must already know the name of the network (SSID)
MAC address whitelist - You can filter out unwanted devices
Encryption (WPA,WPA2)
 What is the SSID
The service set identifier - a unique ID that consists of up to 32 characters and is used for naming wireless networks
Whats the MAC address
Media access control - Used to uniquely identify pieces of hardware
Whats the advantages of a client-server network over a peer-to-peer network?
The server computer can manage security
Files can be stored on the server - accessed at all times even when computers are off
processing some tasks can be performed on servers instead of having to purchase more powerful computers
What does CSMA/CA stand for?
Carrier sense multiple accessÂ
How does CSMA/CA work?
It allows a computer to listen out for transmissions - and if it hears one it waits. Then it checks again after some time and if it doesnât hear anything itâll wait a random short amount of time before sending the data over
What does RTS stand for?
Ready to send
What does CTS stand for?
Clear to send
What does RTS and CTS do?
RTS - when the computer sends an RTS signal it is telling the WAP it is âready to sendâ dataÂ
Then the WAP temporarily stops all over transmissionsÂ
CTS - The WAP sends a CTS signal to the computer telling it that the network is clear then the computer sends over the dataÂ