Part 1, Network technologies Flashcards
what is a client
this is software installed on a users machine that requests information/services from a server
this is software installed on a users machine that requests information/services from a server
client
give three examples of a client installed on a users machine
- file client
- web client (web browser)
- email client
what are these examples of
- file client
- web client (web browser)
- email client
these are examples of clients on a user machine
what is a server
this is software installed on a machine that provides services and information to any client requesting it
this is software installed on a machine that provides services and information to any client requesting it
server
give three examples of a server
- file server
- web server
- email server
what are these examples of
- file server
- web server
- email server
server
what does the term “client-server” mean
the term “client-server” means that a connection has been made between a client and a server and information is being exchanged
the term “—–” means that a connection has been made between a client and a server and information is being exchanged
“client-server”
describe what “layered architecture” is
this is a concept that describes how communication connections work
this is a concept that describes how communication connections work
“layered architecture”
how does “layered architecture” work
this works by describing each connection as a layer where the lower layers provide services to the upper layers. though no layer is concerned with how the other works, just that it provides the correct services
this works by describing each connection as a layer where the lower layers provide services to the upper layers. though no layer is concerned with how the other works, just that it provides the correct services
“layered architecture”
what are the layers in “layered architecture”
a layer is a description of a connection between two peers that must understand each other, each layer therefore has peers that understand each other and have a virtual connection with each other
a layer is a description of a connection between two peers that must understand each other, each layer therefore has peers that understand each other and have a virtual connection with each other
layers in “layered architecture”
using a telephone call give an example of “layered architecture”
telephone call
layer 2: a human operator receives/sends audio to layer 1 (the telephone)
layer 1: telephone receives digital information from another telephone (its peer) and converts it to audio for layer 2 (human operator). also receives audio from layer 2 and converts it to digital information for its peer to understand
telephone call
layer 2: a human operator receives/sends audio to layer 1 (the telephone)
layer 1: telephone receives digital information from another telephone (its peer) and converts it to audio for layer 2 (human operator). also receives audio from layer 2 and converts it to digital information for its peer to understand
example of “layered architecture”
describe what peers are in “layered architecture”
peers in “layered architecture” will have a virtual connection to each other this virtual connection defines the layer they are on and also that any peer on this virtual connection must be able to understand each other
peers in “layered architecture” will have a virtual connection to each other this virtual connection defines the layer they are on and also that any peer on this virtual connection must be able to understand each other
peers are in “layered architecture”
what seven steps might data take on a typical journey
- from laptop
- wireless/wired to home hub/router
- cabinet (roadside box)
- telco (telephone exchange)
- ISP (internet service provider)
- university router
- university server
- from laptop
- wireless/wired to home hub/router
- cabinet (roadside box)
- telco (telephone exchange)
- ISP (internet service provider)
- university router
- university server
typical journey that data might take
how does optical fibre send data
it uses infra-red light to send 1s and 0s
this uses infra-red light to send 1s and 0s
optical fibre
does optical fibre suffer from attenuation
yes optical fibre suffers from attenuation although it can carry data much greater distances before the signal must be regenerated
what is “total internal refraction”
“total internal refraction” is the process that allows fibre optics to carry light it works by not allowing light to escape through the sides of the fibre but only the ends
”—–” is the process that allows fibre optics to carry light. it works by not allowing light to escape through the sides of the fibre but only the ends
“total internal refraction”
what is “on-off keying”
this is a type of modulation used by optical fibre. where a light is turned on and off to represent the data with 1 being when the light is on and 0 being when the light is off
this is a type of modulation used by optical fibre. where a light is turned on and off to represent the data with 1 being when the light is on and 0 being when the light is off
“on-off keying”
what is a “sine wave”
a “sine wave” is a waveform that has a periodically repeating curve
a “—–” is a waveform that has a periodically repeating curve
“sine wave”
what is the “wavelength”
the “wavelength” is the length or distance of one cycle of a wave and is a measure of distance
the “—–” is the length or distance of one cycle of a wave and is a measure of distance
“wavelength”
what does the term “sinusoidal” mean
“sinusoidal” is the term used to describe something that has the form of a sine wave. electromagnetic waves can be sinusoidal and so are called “sinusoidal electromagnetic wave”
”—–” is the term used to describe something that has the form of a sine wave. electromagnetic waves can be “—–” and so are called “”—–” electromagnetic wave”
“sinusoidal”
what is the “period” of a wave
the “period” describes one cycle of a wave in time and is a measure of time
the “—–” describes one cycle of a wave in time and is a measure of time
“period”
what is the “frequency” of a wave
the “frequency” of a wave is the number of cycles it completes within 1 second
the “—–” of a wave is the number of cycles it completes within 1 second
“frequency”
what is “frequency” of a wave measured in
the “frequency” of a wave is measured in hertz(Hz)
the “frequency” of a wave is measured in “—–”
hertz(Hz)
a wave has 1 cycle per second what is its frequency in Hz
1Hz
a wave has a frequency of 1 Hz how many wave cycles per a second is this
1 wave cycle per second
a wave has 1000 cycle per second what is its frequency in Hz
1000Hz or 1 KHz
a wave has a frequency of 1 KHz how many wave cycles per a second is this
1000 wave cycles per second
why are the frequency, period and wavelength all related
they are related because all electromagnetic waves travel at the same speed therefore when one changes the others change relative to the change
what happens when you increase the frequency
increasing the frequency means the wavelength and period will decrease
increasing the frequency means the wavelength will become “—–”
shorter
what happens when you increase the wavelength
increasing the wavelength means the frequency decreases and the period increases
increasing the wavelength means the frequency “—–” and the period “—–”
increasing the wavelength means the frequency decreases and the period increases
mathematically how can you find the frequency when you know the period
frequency = 1 / period
”—–” = 1 / period
frequency
mathematically how can you find the period when you know the frequency
period = 1 / frequency
”—–” = 1 / frequency
period
name three electromagnetic waves that the sun emits
- infra red
- visible light
- ultra-violet
name the 7 electromagnetic waves surrounding and including visible light (lowest to highest frequency)
- radio
- microwaves
- infrared
- visible
- ultra-violet
- x-rays
- gamma rays
name the 7 electromagnetic waves surrounding and including visible light (lowest to highest frequency) and there frequencies
- radio - 10^4 - 10^9
- microwaves - 10^10 - 10^11
- infrared - 10^12 - 10^14
- visible - 10^15 - 10^15
- ultra-violet - 10^16 - 10^17
- x-rays - 10^17 - 10^20
- gamma rays- 10^19 - 10^22
what is a “logarithmic scale”
a “logarithmic scale” is a scale where you have equally spaced values on an axis and each value on the axis is multiplied by the same amount
a “—–” is a scale where you have equally spaced values on an axis and each value on the axis is multiplied by the same amount
“logarithmic scale”
what must you be careful with when using “logarithmic scale”
when using “logarithmic scales” you must be careful with how you interpret data. because each value is multiplied it means the scale is not equal
when using “—–” you must be careful with how you interpret data. because each value is multiplied it means the scale is not equal
“logarithmic scale”
how do you find the range of a frequency band
to find the range of a frequency band you find the difference of the two ends of the frequency band
when the frequency range has been found what is it known as and what is it measured in
the frequency range of a frequency band is known as its “bandwidth” and is measured in Hz
the frequency range of a frequency band is known as its “—–” and is measured in “—–”
the frequency range of a frequency band is known as its “bandwidth” and is measured in Hz
what does a greater bandwidth of a frequency band determine
a greater bandwidth of a frequency band means that it has more capacity and so if used to carry communication data it has the potential to carry more bits per second
a greater bandwidth of a frequency band means that it has “—–” and so if used to carry communication data it has the potential to “—–”
a greater bandwidth of a frequency band means that it has more capacity and so if used to carry communication data it has the potential to carry more bits per second
what is “modulation”
“modulation” is the modification of a wave or signal so that it can be used to carry data
”—–” is the modification of a wave or signal so that it can be used to carry data
“modulation” is the modification of a wave or signal so that it can be used to carry data
name a simple form of “modulation” and one other method
one simple form of “modulation” is “on-off keying” another method of “modulation” might be using two different frequencies to represent a 1 and a 0
one simple form of “modulation” is “—–” another method of “modulation” might be “—–”
one simple form of “modulation” is “on-off keying” another method of “modulation” might be using to different frequencies to represent a 1 and a 0
what is “wavelength division multiplexing (WDM)”
“wavelength division multiplexing (WDM)” is used to increase the data rate of one fibre optic cable. it does this by having two separate sources each using a different frequency send there signal down the same fibre optic cable. when the signal reaches the receiver there is a filter which separates the two frequencies so they can be read as two separate signals
”—–” is used to increase the data rate of one fibre optic cable. it does this by having two separate sources each using a different frequency send there signal down the same fibre optic cable. when the signal reaches the receiver there is a filter which separates the two frequencies so they can be read as two separate signals
“wavelength division multiplexing (WDM)” is used to increase the data rate of one fibre optic cable. it does this by having two separate sources each using a different frequency send there signal down the same fibre optic cable. when the signal reaches the receiver there is a filter which separates the two frequencies so they can be read as two separate signals
what is meant y the term “multiplexing”
“multiplexing” means that multiple sources are sharing a single communications medium (such as fibre optic cable)
”—–” means that multiple sources are sharing a single communications medium (such as fibre optic cable)
“multiplexing” means that multiple sources are sharing a single communications medium (such as fibre optic cable)
what is “dense wavelength division multiplexing (DWDM)” and how many channels can it currently have
“dense wavelength division multiplexing (DWDM)” is another method used to increase the data rate (bandwidth) of fibre optics cables. currently this method can carry 100 channels over a single fibre optic cable
”—–” is another method used to increase the data rate (bandwidth) of fibre optics cables. currently this method can carry 100 channels over a single fibre optic cable
“dense wavelength division multiplexing (DWDM)” is another method used to increase the data rate (bandwidth) of fibre optics cables. currently this method can carry 100 channels over a single fibre optic cable
what is a signals strength measured in and what signal strength would a transmitter usually send out
a “signals strength” is measured in watts. a transmitter will usually send a signal of no more than 1W
a “—–” is measured in watts. a transmitter will usually send a signal of no more than 1W
a “signals strength” is measured in watts. a transmitter will usually send a signal of no more than 1W
what type of attenuation do both metallic wire and optical fibre suffer from
“metallic wire” and “optical fibre” both suffer from exponential decay
”—–” and “—–” both suffer from exponential decay
“metallic wire” and “optical fibre” both suffer from exponential decay
what is “exponential decay”
“exponential decay” is where a signal strength weakens by a regular factor over a particular distance
”—–” is where a signal strength weakens by a regular factor over a particular distance
“exponential decay” is where a signal strength weakens by a regular factor over a particular distance
a signal is sent out at 0.2W it has a decay of a factor of 10 every 500M, after 500M what will the signal strength be
the signal strength will be 0.2 / 10 = 0.02W
which will have a higher signal loss
- metallic cable with low frequency being sent
- metallic cable with high frequency being sent
- metallic cable with high frequency being sent
in general “metallic cables” have higher signal loss the higher the frequency used. this means when sending higher data rates the signal will lose power quicker
in general “—–” have higher signal loss the higher the frequency used. this means when sending higher data rates the signal will lose power quicker
in general “metallic cables” have higher signal loss the higher the frequency used. this means when sending higher data rates the signal will lose power quicker
what is “coaxial cable”
“coaxial cable” is a type of metallic cable with a solid metallic core that is surrounded by insulation then foil then copper braid. it is designed to carry high frequency signals
”—–” is a type of metallic cable with a solid metallic core that is surrounded by insulation then foil then copper braid. it is designed to carry high frequency signals
“coaxial cable” is a type of metallic cable with a solid metallic core that is surrounded by insulation then foil then copper braid. it is designed to carry high frequency signals
what is the attenuation rate of high quality coaxial cable at 2 Mbps
high quality coaxial cable at 2Mbps has an attenuation rate of a factor of 10 every 10Km
”—–” has an attenuation rate of a factor of 10 every 10Km
high quality coaxial cable at 2Mbps has an attenuation rate of a factor of 10 every 10Km
what is the attenuation rate of high quality coaxial cable at 200Mbps
high quality coaxial cable at 200Mbps has an attenuation rate of a factor of 10 every 1KM
”—–” has an attenuation rate of a factor of 10 every 1KM
“high quality coaxial cable at 200Mbps” has an attenuation rate of a factor of 10 every 1KM
what is the attenuation rate of optical fibre
“optical fibre” has an attenuation rate of a factor of a factor of 10 approximately every 30KM
”—–” has an attenuation rate of a factor of a factor of 10 approximately every 30KM
“optical fibre” has an attenuation rate of a factor of a factor of 10 approximately every 30KM
what is one factor that determines how much power a receiver will need in order to read the signal correctly
in general the higher the frequency (data rate) then the stronger the signal has to be for the receiver to read the signal correctly
in general the “—–” then the stronger the signal has to be for the receiver to read the signal correctly
in general the higher the frequency (data rate) then the stronger the signal has to be for the receiver to read the signal correctly
what is a “regenerator”
a “regenerator” will detect an attenuated signal and produce a fresh full signal for the next leg of its journey
a “—–” will detect an attenuated signal and produce a fresh full signal for the next leg of its journey
a “regenerator” will detect an attenuated signal and produce a fresh full signal for the next leg of its journey
