Cwna 106 Exam Essentials

Front 1

Chapter 1 essentials

Back 1

1. Know the four industry organizations.

2. Understand core, distribution, and access

3. Understand wavelength, frequency, amplitude, and phase.

4. Understand the concepts of modulation.

Front 2

Responsibilities of ITU-R

Back 2

> Global Spectrum management

>Ensures interference free communication on land, sea and skies

Front 3

Name Standard Organizations

Back 3

1. ITU-R :International Telecommunication Union Radio Sector

2. FCC: Federal Communications Commission

3. IEEE: Institute of Electric & Electronic Engineers

4. IETF: Internet Engineering Task Force

5. ISO: International Organization for Standardization

6: Wi-Fi Alliance

Front 4

ITU-R responsibilities

Back 4

> Global spectrum management

> Ensures interference free communications on land, sea and skies

Front 5

What is FCC and what are their responsibilities

Back 5

>Its a communication regulatory domain in US

>w.r.t wireless, FCC regulates the usage of radio signals used for communication

Front 6

Name the 6 areas in wireless where FCC regulates on

Back 6

1. Frequency

2. Bandwidth

3. Maximum power of Intentional Radiator(IR)

4. Maximum EIRP

5.Use Indoor or Outdoor

6. Spectrum sharing

Front 7

Which organization is responsible for creating WLAN or any standards/protocols?

Back 7

IEEE

Front 8

What is RFC stands for?

Back 8

>Request For Comments

>provided by IETF

Front 9

Responsibilities of IETF

Back 9

To make internet better

Front 10

Who created OSI model

Back 10

ISO

Front 11

Wi-Fi alliance responsibility

Back 11

Ensure interoperability of WLAN devices by certification testing

Front 12

How many layers does OSI model have?

Back 12

>Seven

Application,Presentation,Session,Transport,Network,Data link(LLC+MAC),Physical

Front 13

WLAN operates in which layer of OSI model?

Back 13

Layer 2

Front 14

Which are the 3 layers in internetworking model?

Back 14

Core, Distribution and Access

Front 15

Client node a.k.a end user packet delivery is performed by _____layer

Back 15

Access layer

Front 16

Core layer functions are ____

Back 16

>reliable delivery of packets to distribution layer and out the network

>high speed switching

Front 17

Packet manipulation is done _____layer

Back 17

Distribution layer

Front 18

Out of Core, Distribution & Access which layer is slower and which one is faster

Back 18

Access layer is slower

Core layer is faster

Front 19

Commonly Wi-Fi is implemented in which layer of internetworking architecture

Back 19

Access layer

Front 20

An 802.11 Bridge link is an example for wireless technology being used in ______ layer.

Back 20

Distribution layer

Front 21

Which are the different properties of a wave?

Back 21

1. Amplitude

2. Wavelength

3. Frequency

Front 22

Distance from rest position to crest is known as ___ of a wave

Back 22

Amplitude

Front 23

Distance travelled by wave when it completes one cycle

Back 23

Wavelength

Front 24

Frequency is ___

Back 24

Number of occurrence of a wave per second at a specific point

Front 25

____ is used to tell relative displacement between or among waves of same frquency

Back 25

Phase

Front 26

Modulation techniques are also known as keying methods. True or False

Back 26

True

Front 27

Which are the different keying methods used in WLAN?

Back 27

ASK: Amplitude Shift Keying

FSK: Frequency Shift Keying

PSK: Phase Shift Keying

Front 28

Current State and State Transition are the 2 different techniques used by keying methods to represent data. True or False

Back 28

True

Front 29

ASK & FSK uses ____ state technique

Back 29

Current State

Front 30

Out of ASK, FSK, PSK which is more effected by noise

Back 30

ASK

Note:

When interference occurs it directly affects amplitude of the signal. A change in amplitude due to noise will lead to misinterpretation of data at the receiver

Front 31

PSK is widely used in 802.11. True or False

Back 31

True

Front 32

Current state technique:

current state of a signal is used to represent 0s and 1s

Analogy:

A door can be used to represent 0s and 1s. An opened door represents 0 and closed door represents 1

Eg: ASK(AM/FM), FSK

Back 32

Statement: Modulation technique

Front 33

State transition technique:

Change or transition of a state is used to represent 0s and 1s

Analogy:

A door can be used to represent 0s and 1s. Here moving door(opening or closing) represents 0 and still door(opened or closed) represents 1

Eg: PSK

Back 33

Statement: Modulation technique

Front 34

Chapter 2 Essentials

Back 34

1. wavelength, frequency, amplitude, and phase

2. RF behaviors

Wave propagation, Absorption, Reflection Scattering, Refraction, Diffraction, Loss (attenuation), Free space path loss, Multipath, Gain (amplification)

Front 35

Measure of how effective an antenna is at receiving the power of radio waves is known as____

Back 35

Aperture

Front 36

Higher the frequency, lower the wavelength will be. True or False

Back 36

True

Front 37

In real world waves with higher frequency attenuate more than waves with lower frequency. True or False

Back 37

True

Front 38

Unit of frequency is ____

Back 38

Hertz(Hz)

Front 39

2.4 GHz WLAN radios, the RF signal is oscillating2.4 billion times per second. True or False

Back 39

True

Front 40

Signal strength or power of a signal is known as___

Back 40

Amplitude

Front 41

Amount of initial amplitude that leaves the radio transmitter is known as___ amplitude and received signal strength is known as ___amplitude

Back 41

Transmit, Recieve

Front 42

RF signal strength measurements taken during site survey is an example for ____ amplitude.

Back 42

Recieve

Front 43

Transmit power range of indoor 802.11 radios range is ____

Back 43

1mW to 100mW

Front 44

Phase can be measured in distance, time or degrees. True or False

Back 44

True

Front 45

Name the nine Radio Frequency Behaviours

Back 45

1. Absorption

2. Reflection

3. Scattering

4. Refraction

5. Diffraction

6. Free space path loss

7. Multipath

8. Attenuation

9. Gain

Front 46

The manner in which RF signal moves is known as____

Back 46

propogation behaviour

Front 47

Why WLAN Engineer should be aware of RF propagation behaviour?

Back 47

For the proper placement of AP, choosing right antenna type and for monitoring wireless performance

Front 48

Which one these will aborb more

1. Dry wall

2. Brick and Concrete

3. Water

Back 48

Brick and Concrete

Front 49

When a wave hits a smooth object larger than its wavelength and bounce in a different direction is known as___

Back 49

Reflection

Front 50

Microwave frequency range

Back 50

1GHz to 300GHz

Front 51

Two types of RF reflection

Back 51

Sky wave and microwave

Front 52

What type of reflection will come across in 802.11 ?

Back 52

microwave

Front 53

Sky wave reflection occurs for waves below 1GHz of frequency. True or False

Back 53

True

Front 54

Scattering is analogous to multiple reflections. True or False

Back 54

True

Front 55

Common reasons for scattering

Back 55

Smog in atmosphere, sand in desert

Due to uneven surfaces:

Chain link fences, wire mesh in stucco walls or old plaster walls, tree foliage, rocky terrains

Front 56

Bending of RF waves when it pasess through medium of different density is known as ___

Back 56

Refraction

Front 57

3 main causes of refraction

Back 57

1. Water vapour

2. Changes in air temperature

3. Changes in air pressure

Front 58

Bending of RF signal around an object is known as ___

Back 58

Diffraction

Front 59

Diffraction is caused by partial blockage of RF signal. True or False

Back 59

True

Front 60

The place sitting exact behind the RF blockage is known as ___

Back 60

RF shadow

Front 61

Loss of signal strength due to absorption, reflection, negative effects of multipath is known as ___

Back 61

Attenuation

Front 62

Loss in signal strength due to natural broadening of waves is known as

Back 62

Free space path loss

Front 63

Unit of attenuation is expressed in

Back 63

dB

Front 64

According to 6dB rule,doubling the distance will result in ___dB decrease in amplitude

Back 64

6

Front 65

When a signal encounters an object it may reflect, scatter.refract or diffract resulting same signal travelling multiple maths arriving receiver at nano seconds difference is known as

Back 65

Multipath effect

Front 66

____ is the time differential between primary signal and reflected signal

Back 66

Delay spread

Front 67

Possible outcomes of multipath are

Back 67

1. Upfade

2. Downfade

3. Nulling

4. Intersymbol interference

Front 68

When the primary signal and reflected signal arrives receiver with 0 to 120 degree phase difference it will result in ___

Back 68

Upfade

Front 69

When the primary signal and reflected signal arrives receiver with 121 to 179 degree phase difference it will result in ___

Back 69

Downfade

Front 70

When the primary signal and reflected signal arrives receiver with 180 degree phase difference it will result in ___

Back 70

Nulling

Front 71

Amplification of a signal is known as ___

Back 71

Gain

Front 72

Gain achieved with the help of amplifier is known as ___

Back 72

Active gain

Front 73

Gain achieved without amplifier and only with antenna is known as ___

Back 73

Passive gain

Front 74

Spectrum analyzer is a ___domain tool for measuring amplitude

Back 74

Frequency

Front 75

Time domain tool used by WLAN Engineers to measure amplitude

Back 75

Oscilloscope

Front 76

Chapter 3 essentials

Back 76

1. Components of RF communication: Transmitter, Receiver, Antenna, Isotropic radiator, Intentional radiator, Equivalent isotropically radiated power(EIRP)

2. Units of power and comparison:

watt,milliwatt,dB,dBi,dBd,dBm,inverse square law

3. RF Math: Rules of 10s and 3s

4. Noise Floor

5. SNR

6. RSSI

7. Link budget

8. Fade margin/system operating margin

Front 77

Higher the transmit power, higher the transmit amplitude and farther the wave can travel. True or False

Back 77

True

Front 78

Transmit power of a wireless transmitter is regulated by ___

Back 78

FCC

Front 79

Functions of antenna

Back 79

Transmit and receive signals to and from transceiver

Front 80

Access points, client adapters, wireless bridge links are examples for transreceivers. True or False

Back 80

True

Front 81

A point source which radiates signal equally in all directions is known as ___ radiator

Back 81

isotropic radiator

Front 82

Transceiver is a single component or device which does two different functions, transmitter and receiver. True or False

Back 82

True

Front 83

Transmitter modulates input data/signal and transmit through antenna. The resulting wave after modulation is known as

Back 83

Carrier wave

Front 84

Usually carrier wave higher frequency than input signal. True or False

Back 84

True

Front 85

The final component in the wireless medium who is responsible for demodulating signal into bits and bytes and fed into computer

Back 85

Receiver

Front 86

Anything which generates RF energy is called Intentional Radiator(IR) . True or False

Back 86

False

Front 87

A device that intentionally generates and emits RF energy by induction or radiation is called Intentional Radiator

Back 87

Statement: Definition of IR by FCC

Front 88

Components of IR

Back 88

Everything between transmitter and antenna excluding antenna and including transmitter.

components include transmitter,all cables and connectors, amplifiers, attenuators, lightning arrestors, grounding between transmitter and antenna.

Front 89

Power of IR is measured in

Back 89

mW or dBm

Front 90

Power of IR is the sum of power of all components including transmitter,cables and connectors. True or False

Back 90

True

Front 91

Power of IR is measured at ___

Back 91

connector that provides input to antenna

Front 92

Highest RF signal that is transmitted from antenna is known as ___

Back 92

EIRP

Front 93

Product of power supplied to antenna and antenna gain in a given direction relative to an isotropic antenna

Back 93

FCC definition of EIRP

Front 94

Units of transmit and received power measurements are absolute power measurements

Back 94

Statement: Absolute power measurement

Front 95

Units of comparison are measurements of change in power

Back 95

Statement: Change in power measurement

Front 96

Watt,mW, dBm are ___

Back 96

units of power(absolute)

Front 97

dB,dBi,dBd are units of ___

Back 97

change in power(units of comparison)

Front 98

Antenna gain is expressed in ___

Back 98

dBi

Front 99

Antenna gain is always positive. True or False

Back 99

True

Front 100

Antenna power is always expressed in gain not power

Back 100

Statement: Antenna facts

Front 101

Decibel gain w.r.t an isotropic antenna is known as ___

Back 101

dBi

Front 102

Antenna radiates equally in all directions. True or False

Back 102

False

Front 103

Antenna gain or dBi is measured at the strongest point or focus point of antenna signal

Back 103

Statement

Front 104

Antenna with dBi = 0 is also known as ___

Back 104

no gain or unity gain antenna

Front 105

Antenna focus more energy on one side than the other. So the dBi of antenna will be always positive gain and not loss. True or False

Back 105

True

Front 106

dBi value of 2.4GHz half-wave dipole antenna is ___

Back 106

2.14

Front 107

dBd is antenna gain w.r.t dipole antenna

Back 107

Statement

Front 108

dBi, dBd relationship

Back 108

dBi= 2.14+dBd

Front 109

Both dBi and dBd are used to express antenna gain. True or False

Back 109

True

Front 110

dBm is decibel relative to 1mW

Back 110

Statement: dBM

Front 111

Since dBm is relative measurement to a known value 1mW, dBm is an absolute measurement.True or False

Back 111

True

Front 112

0dBm = __mW

Back 112

1mW

P(in mw) = 10^(PdB/10)

Front 113

+dBm indicates value is greater than 1mW. True or False

Back 113

True

Front 114

-dBm indicates value is less than 1mW. True or Falsse

Back 114

True

Front 115

If you double the distance between transmitter and receiver amount of usable signal will ___ by 6dB

Back 115

decrease

Front 116

6dB rule

Back 116

+6dB doubles the distance of usable signal

-6dB halves the distance of usable signal

Front 117

Rules of 3s and 10s

Back 117

1. For every 3dB gain, double(x2) the absolute power in mW

2. For every 3dB loss, halve(÷ 2) the absolute power in mW

3. For every 10dB gain, multiply absolute power in mW by 10

4. For every 10 dB loss, divide absolute power in mW by 10

Front 118

RF Math summary

Back 118

dBm=10 log(Power in mW)

Power in mW=10^(dBm/10)

3 dB gain = mW x 2

3 dB loss = mW ÷ 2

10 dB gain = mW × 10

10 dB loss = mW ÷ 10

Front 119

Steps involved in calculating IR and EIRP

Back 119

1. Convert mW values in dB

2. Apply rules of 3s and 10s

Note: All dB values can be added

Front 120

Ambient or background level of radio energy on a specific channel is called

Back 120

Noise floor

Front 121

Noise floor of typical 2.4GHz ISM channel

Back 121

-100dBm

Front 122

Noise floor of 5GHz will be higher than 2.4GHz. True or False

Back 122

False

Front 123

SNR is the ratio between received signal and noise floor. True or False

Back 123

False

Front 124

The difference between received signal and noise floor

Back 124

SNR(signal to noise ratio)

Front 125

Low SNR is one of the reason for layer 2 retransmission and low throughput

Back 125

Statement: SNR facts

Front 126

Good quality signal will have SNR >= 25dB

Back 126

Statement: SNR facts

Front 127

SNR <= 10dB are considered as signal with poor quality

Back 127

Statement: SNR facts

Front 128

RSSI is ___

Back 128

recieved signal strength indicator

Front 129

RSSI is expressed in ___

Back 129

dBm

Front 130

Higher the RSSI greater the signal quality

Back 130

Statement: RSSI facts

Front 131

power level of RF signal required to be successfully received by the receiver is called as __

Back 131

RSSI

Front 132

Range of RSSI value ___

Back 132

0 to 255

Front 133

Signal with high data rate are more susceptible to corruption. True or False

Back 133

True

Front 134

Device used by WLAN engineers to measure noise floor, SNR

Back 134

spectrum analyzer

Front 135

The sum of all planned expected gains and losses from the transmitting radio, through the RF medium, to the receiver radio

Back 135

Link budget

Front 136

Purpose of calculating link budget

Back 136

To make sure final received signal is above the receiver sensitivity threshold of receiver radio

Front 137

Fade margin = received signal strength - receiver sensitivity of the receiver

Back 137

Statement: Fade margin

Front 138

Minimum fade margin required

Back 138

10dB

Front 139

For transmissions higher than 5 miles, recommended fade margin for reliable communication will be ___

Back 139

25dB

Front 140

Best practice followed by WLAN engineers for indoor environmentby choosing fade margin ____ , for reliable communication

Back 140

5dB greater than receiver's sensitivity amplitude

Front 141

Link budget and Fade margin are the 2 essential things which should be taken care of by WLAN engineers for outdoor deployment. True or False

Back 141

True

Front 142

WLAN vendors use RSSI thresholds to trigger which radio card behaviors?

Back 142

Roaming and Dynamic Rate Switching(DRS)

Front 143

Chapter 4 essentials

Back 143

1. Four antenna types: Omni directional.semi directional,highly directional,sector

2. Azimuth and elevation charts

3. Key concerns while installing point-to-point communication: Visual LOS, RF LOS, Fresnel zone, Earth bulge, Antenna polarization

4. VSWR, antenna mounting issues, antenna accessories and their roles

Front 144

To assist potential buyers, antenna manufactures creates antenna radiation pattern for their antennas known as polar chart or antenna radiation envelopes.

Back 144

Statement: Antenna radiation charts

Front 145

Azimuth and elevation charts are example for ___

Back 145

polar charts or antenna radiation pattern charts

Front 146

Which chart will give us top-down-view of antenna radiation pattern?

Back 146

Azimuth chart

Front 147

Which chart will give us side view of antenna radiation pattern?

Back 147

Elevation chart

Front 148

Radiation charts are drawn by keeping antenna on the center of the chart. True or False

Back 148

True

Front 149

Reference plane on which Azimuth chart is drawn.

Back 149

H-plane

Front 150

Reference plane on which Elevation chart is drawn.

Back 150

E plane

Front 151

E plane gives us the side view of antenna radiation pattern with antenna in the centre of the chart

Back 151

Statement: reference plane for antenna radiation pattern

Front 152

H plane gives us top view of antenna radiation pattern with antenna in the centre of the chart

Back 152

Statement: reference plane for antenna radiation pattern

Front 153

Measurement which tells us how broad or narrow is the focus of the antenna is called ____

Back 153

Beamwidth

Front 154

Beamwidth is measured from the centre or at the strongest point of the antenna signal to each points along vertical axis and horizontal axis where signal decreases by half power(-3dB)

Back 154

Statement: beamwidth

Front 155

The point at which signal power becomes half the power is called half-power-points

Back 155

Statement:Beamwidth

Front 156

The distance between half power points in vertical axis is measured in

Back 156

degrees

Front 157

The distance between half power points in horizontal axis is measured in

Back 157

degrees

Front 158

3 types of antennas

Back 158

1. Omni directional

2. Semi directional

3. Highly directional

Front 159

Which type of antenna gives us 360 degrees of coverage?

Back 159

omni directional

Front 160

Type of antenna which provides directional coverage over a large area

Back 160

semi directional

Front 161

Type of antenna which is generally preferred in point-to-point communication

Back 161

Highly directional antennas

Front 162

Dipole antenna a.k.a rubber duck antenna is an example for ___

Back 162

omni directional antennas

Front 163

Antenna whose RF radiation pattern is similar to that of isotropic radiator

Back 163

Dipole antenna

Front 164

Higher the dBi or dBd value of antenna higher will be the focus of the signal. True or False

Back 164

True

Front 165

Omnidirectional antennas have great horizontal coverage and less vertical coverage

Back 165

Statement: Omni directional antenna

Front 166

Vertical beamwidth of omni directional antenna ranges from

Back 166

7 to 80 degrees

Front 167

Patch, Panel, Yagi are examples for ____ type of antennas

Back 167

semi directional

Front 168

Type of antennas suitable for short to medium distance communications

Back 168

Semi directional

Front 169

Type of antennas preferred in libraries with large corridors and shelves,hallways where omni directional antennas are ineffective to provide proper coverage

Back 169

Planar antennas

Front 170

Patch and Panel antennas are commonly referred as ___ antennas

Back 170

Planar antennas

Front 171

Horizontal beamwidth of patch/panel antennas

Back 171

30 to 180 degrees

Front 172

Vertical beamwidth of patch panel antennas

Back 172

6 to 90 degrees

Front 173

Antennas ideal for high density environment like gymnasium, schools, hallways when 802.11n or 11ac is deployed

Back 173

MIMO patch antennas

Front 174

MIMO patch antennas are mounted from the ceiling downward to provide coverage on tight sectors

Back 174

Statement: MIMO patch antenna

Front 175

What type of antenna is shown in pic

Back 175

Yagi uda antenna(Semi directional)

Front 176

Type of antenna shown in pic

Back 176

Panel antenna (semi directional)

Front 177

Name the antenna

Back 177

rubber duck or half wave dipole antenna

Front 178

Antenna type shown in pic

Back 178

parabolic dish(highly directional)

Front 179

Antenna type shown in pic

Back 179

Grid antenna(highly directional)

Front 180

The spacing of wires in grid antenna is determined by the wavelength of the frequencies that antenna is designed for

Back 180

Statement: Grid antenna

Front 181

Out of 2 antenna types parabolic dish and grid, which one is more susceptible to high wind environment?

Back 181

parabolic dish

Note: Because the spacing between the wires, grid antennas are less affected by high wind environment

Front 182

Sector antennas are high gain semi directional antennas which has pie shaped coverage area.

Back 182

Statement: Sector antennas

Front 183

Sector antennas are placed in the centre, where RF coverage area is required, by keeping antennas back to back

Back 183

Statement: Sector antennas

Front 184

Combining sector antennas, so that each coverage pie area of each antenna forms a 360 degree coverage is called sector array

Back 184

Statement: Sector antennas

Front 185

The main disadvantage in a sector array is, back lobes of each antenna's radiation pattern interfere with each other. True or False

Back 185

False

Note: Radiation formed at back side of sector antenna are minimal and doesn't cause any interference or have least impact

Front 186

Sector antennas typically have a gain of ___dBi

Back 186

10 dBi

Front 187

Horizontal beamwidth of sector antennas

Back 187

60 to 180 degrees

Front 188

Vertical beamwidth of sector antennas

Back 188

7 to 17 degrees

Front 189

Name the antenna type used in picture

Back 189

Sector antenna

Front 190

To provide RF coverage in outdoor areas, stadium ____ antennas are preferred

Back 190

Sector

Front 191

A group of two or more antennas that are integrated together to provide coverage is generally known as ___

Back 191

antenna arrays

Front 192

3 types of beamforming

Back 192

1. Static beamforming

2. Dynamic beamforming

3. Transmit beamforming

Front 193

Beamforming is method of concentrating RF energy by focusing the RF transmission from antenna to receiver

Back 193

Statements: Beamforming

Front 194

Beamforming achieved by clustering multiple directional antennas to provide a fixed radiation pattern,aimed away from centre or location

Back 194

Static beamforming

Front 195

Indoor sectorized array is an example for ___

Back 195

static beamforming

Front 196

smart antenna or beam steering is a technology used in ___ beamforming

Back 196

dynamic

Front 197

In dynamic beamforming adaptive antenna arrays maneuvers radiation pattern in the direction of the receiver.

Back 197

Statements: Dynamic beamforming

Front 198

Unlike static beamforming whose radiation patterns are fixed, radiation pattern varies frame-by-frame in dynamic beamforming. True or False

Back 198

True

Front 199

Wi-Fi vendor Xirrus is an example for manufacturing indoor sectorized array solution

Back 199

Statement: Static beamforming

Front 200

Ruckus wireless is an example for Wi-Fi vendors who is capable of providing dynamic beamforming solutions

Back 200

Statement: Dynamic beamforming

Front 201

Transmit Beamforming:

By carefully adjusting phase of signals transmitted from each antenna so that, when signals arrive at receiver are in phase.

Back 201

Statement: TxBf

Front 202

2 types of beamforming

Back 202

implicit and explicit

Front 203

802.11n uses what type of beamforming

Back 203

Both implicit and explicit

Front 204

802.11 ac uses what type of beamforming

Back 204

explicit

Front 205

Light travels from one to another point in an unobstructed straight line called ___

Back 205

Visual line of sight(LOS)

Front 206

RF line of sight is also known as ___

Back 206

Fresnel zone

Front 207

Imaginary elongated football shaped area around visual line of sight is called ___

Back 207

Fresnel zone

Front 208

Fresnel exists both above and below visual los. True or False

Back 208

True

Front 209

It is recommended practice while mounting outdoor point-to-point communication that 1st fresnel zone is not obstructed by buildings, trees or any other obstacles.

Back 209

Statement: Fresnel zone

Front 210

Size of fresnel zone is a function of distance between points and frequency being used

Back 210

Statement: Fresnel zone

Front 211

Multiple fresnel zone exists around the primary or first fresnel zones.

Back 211

Statement: Fresnel zone

Front 212

RF signal at first fresnel zone is in phase with point source signal

Back 212

Statement: Fresnel zone

Front 213

All the odd fresnel zones are in phase with point source and all the even fresnel zones are out of phase with the point source signal. True or False

Back 213

True

Front 214

Earth bulge is earth's curvature.

Back 214

Statement: Earth bulge

Front 215

Earth bulge should be considered when distance between point to point communication are greater than 7 miles

Back 215

Statement: Earth bulge

Front 216

Which all factors are considered when calculating antenna height in feet

Back 216

Fresnel zone, Earth bulge, Height of obstacle

Note:

H = obstacle height + earth bulge + Fresnel zone

Front 217

Antenna diversity is also known as ___

Back 217

spatial diversity

Front 218

Antenna diversity works only if receiver has multiple antennas. True or False

Back 218

True

Front 219

Antenna diversity is introduced to avoid/minimize negative effects of ___

Back 219

multipath

Front 220

When transceiver receives multiple copies of same signal from multiple antennas, it choose signal from those antenna which has the best signal quality. This technique is commonly used in pre-802.11n and known as ___

Back 220

switched diversity

Front 221

switched diversity is also known as

Back 221

receive diversity

Front 222

While using receive diversity signal with best amplitude is chosen by the receiver. True or False

Back 222

True

Front 223

While using switched diversity during transmission, same signal is sent across all the antennas. True or False

Back 223

False

Note:

Only one antenna is used.

The antenna in which last best received signal was heard is used.

Front 224

switched diversity used in transmission is known as ___

Back 224

transmit diversity

Front 225

If implemented, access point when making use of antenna diversity, all the antennas should have same gain, same orientation and distance between antennas should be a factor of wavelength(1/4, 1/2,1,2)

Back 225

Statement: antenna diversity

Front 226

MIMO stands for

Back 226

Multiple Input Multiple Output

Front 227

MIMO took positive effects of ___ to increase throughput

Back 227

multipath

Front 228

MIMO was first introduced in

Back 228

802.11n

Front 229

While transmitting using antenna diversity out of all antennas only one antenna is used. But in MIMO all the antennas are used concurrently

Back 229

Statement: MIMO Vs Antenna diversity

Front 230

3 key components associated with antenna installation

Back 230

1. Voltage Standing Wave Ratio(VSWR)

2. Signal loss

3. Mounting of antenna

Front 231

Voltage standing wave ratio is a measurement of change in impedance of an AC signal. True or False

Back 231

True

Front 232

Voltage standing waves are generated due to impedance mismatch between transmitter,cable and antenna

Back 232

Statement: VSWR

Front 233

Numerical expression for VSWR

Back 233

VSWR = Vmax/Vmin

Maximum voltage across the line /Min voltage across the line

Front 234

Ideal value for VSWR

Back 234

1:1

Front 235

Typically VSWR value ranges from

Back 235

1.1:1 to 1.5:1

Front 236

The ratio between voltage of reflected wave and incident wave is known as

Back 236

reflection coefficient

Front 237

reflection coefficient is denoted by

Back 237

greek letter rho (ρ).

Front 238

Difference between power sent to antenna and power reflected back is known as

Back 238

return loss

Front 239

Return loss is expressed in

Back 239

dB

Front 240

VSWR may cause decreased signal strength, erratic signal strength , transmitter failure if not protected

Back 240

Statement: VSWR

Front 241

Resulting signal reaching the antenna will be larger if VSWR is larger. True or False

Back 241

False

Front 242

Key areas to be concerned while installing antennas

Back 242

1. Placement

2. Mounting

3. Appropriate use and environment

4. Orientation and alignment

5. Safety

6. Maintenance

Front 243

2 standards that designates how device can stand up against harsh environments

Back 243

1. IP Rating(Ingress Protection Rating)

2. NEMA Rating(National Electrical Manufacturers Association)

Front 244

IP rating is denoted by IP followed by two digits or a digit and one or two letters

Example: IP66

Back 244

Statement: IP rating

Front 245

You have been provided an antenna with IP rating IP66. What does it indicates?

Back 245

First digit indicates how far the antenna can withstand intrusion against solid particles like dust on a scale of 0 to 6

Second digit indicates water resistance capability on a scale of 0 to 8

Front 246

You have been provided an antenna with IP rating IPX. What does it indicates?

Back 246

It means no protection is provided against intrusion of solid particles and water

Front 247

Rating of NEMA is in the form of number or number followed by a letter

Back 247

Statement : NEMA

Front 248

Which are the features included in Nema ratings that are not present in IP rating?

Back 248

Corrosion resistance

Gasket aging

Construction practices

Front 249

Atex directive pertains to equipment and protective systems that are intended to be usedin potentially explosive atmospheres.

Back 249

ATEX 95

Front 250

Atex directive pertains to the workplace and is intended to protect and improve thesafety and health of workers at risk from explosive atmospheres.

Back 250

ATEX 137

Front 251

NEC is __

Back 251

National Electrical Code

Front 252

__ is a standard for safe installation of electrical equipment and wiring

Back 252

NEC

Front 253

NEC classifies hazardous location by type condition and nature. Name them those classifications

Back 253

1. Class I gas or vapor

2. Class II dust

3. Class III fibers and flyings

Front 254

To prevent from water damage cold shrink tubing is used rather than hot shrink tubing. The

reason is __

Back 254

cable can be damaged by the heat that is necessary to shrink the wrapping.

Front 255

Silicone is not used to prevent the cable from water damage. The reason is __

Back 255

air bubbles can form inside silicone and moisture can be formed

Front 256

Cable manufacturers will list range of frequencies that cable can support and is generally known as ___

Back 256

Frequency response

Front 257

LMR 900 cable is generally used for __GHz

Back 257

5

Front 258

LMR 1200 is used for ___GHz

Back 258

2.4

Front 259

Higher the frequency of signal, higher will be attenuation caused by the cable. True or False

Back 259

True

Front 260

RF connectors generally add __dB of insertion loss

Back 260

1/2

Front 261

Antenna accessory which takes a RF signal and divides into two or more seperate signals is known as

Back 261

splitter

Front 262

The increase in gain by applying electrical power to signals by an amplifier is known as

Back 262

active gain

Front 263

It is a recommended practice to install amplifier as close to antenna to prevent cable loss.

Back 263

Statement: amplifier

Front 264

Antenna accessory which is used to decrease the amount of signal radiating from antenna

Back 264

attenuator

Front 265

Two different type of attenuator

Back 265

1. Fixed loss attenuator

2. Variable loss attenuator with a dial to control dB loss

Front 266

__ is used to calculate fade margin in outdoor site surveys.

Back 266

variable attenuator

Front 267

Lightning arrestors are not capable of direct lightning strike. True or False

Back 267

True

Front 268

Lightning arrestors protect against surges from 5000amps to 50 volts

Back 268

Statement: Lightning arrestor

Front 269

As per IEEE, a lightning arrestor should be capable of redirecting transient current within 8micro seconds

Back 269

Statement: Lightning arrestor

Front 270

Lightning arrestor should be placed close to antenna with all other communication devices like amplifiers, attenuators installed between transceiver and lightning arrestor . True or False

Back 270

True

Front 271

Antenna accesories

Back 271

1. Cables

2. Connectors

3. Splitter

4. Amplifier

5. Attenuator

6. Lightning arrestor

7. Grounding rods and wires

Front 272

Azimuth chart is prepared in reference with H-plane. What is this H denotes?

Back 272

Horizontal

Front 273

Semi directional antennas reduce reflection and thereby reduces negative effects of multipath. True or False

Back 273

True

Front 274

Chapter 5 essentials

Back 274

1. Know different types of spread spectrum technologies used in each PHY

2. Required rates and supported rates of each PHY

3. Frequency band of each PHY

4. TPC and DFS

5. Pre-RSN and RSN security standards

Front 275

The original 802.11 standard was first published in June 1997 as IEEE 802.11-1997 standard and is often referred as 802.11 prime.

Back 275

Statement: 802.11 standard

Front 276

The most recent iteration of 802.11 standard is __

Back 276

IEEE 802.11-2012

Note: As per cwna 106 exam latest 802.11 is 2012. But the most recent version is IEEE 802.11-2016 which incorporates 11ac into it.

Front 277

Data rate is number of bits leaving physical layer during single transmission.

Back 277

Statement: Data rate

Front 278

Data rate is expressed in ___

Back 278

Mbps

Front 279

Due to medium contention overhead, MAC layer overhead and interference, throughput will be always 30 to 40 lesser than bandwidth. True or False

Back 279

True

Front 280

Data rate supported by 802.11 b radios

Back 280

1, 2, 5.5, 11Mbps

Front 281

PHY techniques introduced in 802.11 b to achieve high data rate

Back 281

HR-DSSS

Front 282

Complementary code keying and Barker code are modulation schemes used in ___

Back 282

802.11 b

Front 283

Optional modulation scheme introduced in 802.11 b

Back 283

PBCC

Front 284

802.11 a operates in ___GHz band

Back 284

5GHz

Front 285

RF technology introduced in 802.11 a

Back 285

OFDM

Front 286

5GHz band in which WLAN operates is known as

Back 286

UNII bands

Front 287

UNII stands for __

Back 287

Unlicensed National Information Infrastructure

Front 288

What are the supported rates of 802.11 a

Back 288

6, 9, 12, 18, 24, 36, 48, 54Mbps

Front 289

Mandatory rates for 802.11 a

Back 289

6, 12 ,24

Front 290

PHY technology introduced in 802.11 g

Back 290

ERP-DSSS/CCK, ERP-OFDM

Front 291

802.11g works in __ frequency band

Back 291

2.4 to 2.4835 GHz ISM

Front 292

Supported rates of 802.11 g

Back 292

6, 9, 12, 18, 24, 36, 48, 54

Front 293

Higher rates in 802.11 g is acheived due to ___

Back 293

ERP-OFDM

Front 294

Backward compatibility of 802.11 g with legacy DSS and 802.11b radios is achieved with the help of __PHY technology

Back 294

ERP-DSSS/CCK

Front 295

Two optional PHYs defined in 802.11 g spec

Back 295

ERP-PBCC, DSSS-OFDM

Front 296

802.11 a/g work sin 2.4GHz ISM band. ISM stands for ___

Back 296

Industrial Scientific Medical

Front 297

Country code information is included in Beacons and probe response as a part of ___ amendment

Back 297

802.11 d

Front 298

Radar detection and avoidance technology is introduced in ___ ammendment

Back 298

802.11 h

Front 299

Mechanisms implemented in 802.11 h to avoid radar detection and interference

Back 299

DFS(Dynamic Frequency Selection) and TPC(Transmit Power Control)

Front 300

Frequency band introduced as part of 802.11 h

Back 300

UNII-2 extended

5.47 -5.825

Front 301

RSN stands for __

Back 301

Robust security network

Front 302

Security enhancements addressed in 802.11 i are__

Back 302

1. Data privacy: CCMP,TKIP

2. Data Integrity: MIC

3. Authentication : PSK and 802.1x

Front 303

Wi-Fi alliance certification based on 802.11 i

Back 303

Wi-Fi protected access 2 certification(WPA2)

Front 304

Amendment which allows WLAN operation in 4.9 to 5.091GHz band to conform to the Japanese regulatory authorities

Back 304

802.11 j

Front 305

Available data rates while operating in Japan

Back 305

3, 4.5, 6, 9, 12,18, 24, 27

Front 306

Which are mandatory data rates when using 10MHz channel spacing in Japan

Back 306

3,6,12

Front 307

QoS is defined in which amendment

Back 307

802.11e

Front 308

EDCA and HCCA are the two channel methods defined in 802.11 e

Back 308

Statement: 802.11e

Front 309

EDCA is an extension of DCF and HCCA is an extension of PCF

Back 309

Statement: 802.11e

Front 310

Certification provided by Wi-Fi alliance for QoS

Back 310

WMM certification

Front 311

Fast secure roaming or Fast Basic Service Set Transition(FT) is defined in ___ amendment

Back 311

802.11 r

Front 312

802.11 r is introduced to reduce the delay in roaming while stronger encryption like 802.1x is in use.

Back 312

Statement: 802.11 r

Front 313

RRM or Radio Resource Management was defined in 802.11__ amendment

Back 313

802.11 k

Front 314

Key areas where 802.11 k focus on

Back 314

1. Transmit power control

2. Client statistics

3. Channel statistics

4. Neighbor reports

Front 315

Name the Wi-Fi alliance certification in which 802.11 r and 802.11 k are tested

Back 315

Voice Enterprise

Front 316

802.11 y allows WLAN usage at higher power than the regular 802.11 in the licensed frequency range 3650 MHz- 3700MHz

Back 316

Statement: 802.11 y

Front 317

To avoid interference 802.11 y uses CSMA/CA along with Dynamic STA enablement(DSE) procedures

Back 317

Statement: 802.11 y

Front 318

Amendment 802.11 __ provides unicast,multicast,broadcast management frame protection

Back 318

802.11 w

Front 319

In 802.11 w unicast management frames are protected using ___

Back 319

CCMP

Front 320

In 802.11 w broadcast/multicast management frames are protected using

Back 320

BIP-Broadcast/Multicast Integrity Protocol

Front 321

802.11 p is also known as WAVE. WAVE stands for ___

Back 321

Wireless Access in Vehicular Environments

Front 322

802.11 p operates in 5.850-5.925 GHz frequency

Back 322

Statement: 802.11p

Front 323

802.11 p is introduced for inert vehicular communication

Back 323

Statement: 802.11p

Front 324

STA to STA communication or Direct Link setup is introduced in 802.11 __

Back 324

802.11 z

Note:

DLS allows client stations to bypassthe access point and communicate with direct frame exchanges

Front 325

Wireless Interworking with External Network or WIEN is defined in __amendment

Back 325

802.11 u

Front 326

Wi-Fi alliance certification based on 802.11 u

Back 326

passpoint certification

Front 327

Wireless Network Management is introduced in ___ amendment

Back 327

802.11 v

Front 328

802.11 s introduced ___

Back 328

mesh networking

Front 329

802.11-ae -2012 introduced Quality Management Frames

802.11-aa-2012 introducedGroup Cast Retries

802.11-ad-2012 introduced WiGig

802.11-ac-2013 introduced VHT

802.11-af-2013 introduced wlan operation in TV white space 54MHz-790 MHz

Back 329

Post 2012 ratified amendments

Front 330

802.11 m Task group is intended for__

Back 330

internal maintenance of 802.11 documentation

Front 331

Chapter 6 essentials

Back 331

1. Know all the specs about ISM and UNII bands

2. Know about different spread spectrum technologies like DSSS, FHSS, OFDM

3. Channels 2.4/5GHz, adjacent, non adjacent, overlapping channels

4. Throughput vs bandwidth

Front 332

Frequency ranges of ISM band

Back 332

902-928 MHz: 26 MHz wider. a,k,a Industrial band

2.4-2.5 GHz: 100 MHz wide, a.k.a Scientific band

5.725-5.875 GHz: 150MHz wide, a.k.a Medical band

Front 333

Out of ISM band frequency range , GSM uses which frequency

Back 333

900MHz

Front 334

Baby monitors, wireless telephones, wireless headphones uses ___ frequency range of ISM band

Back 334

900MHz

Front 335

Cordless home telephones, microwaves, baby monitors, wireless video cameras use ___ frequency range of ISM band

Back 335

2.4GHz

Front 336

One of the major disadvantage of using 2.4GHz for wlan is this band is heavily used and there is a huge potential for interference. True or False

Back 336

True

Front 337

IEEE allows 2.4GHz wlan transmission across 14 channels. However local regulatory authority determines which channels can be used. True or False

Back 337

True

Front 338

ISM band which shares the same frequency range with UNII-3

Back 338

5.725 - 5.875 GHz(150 MHz wider)

Note:

UNII-3 band 5.725 - 5.850(125 MHz wider)

Front 339

Consumer devices which operates in 5.8GHz cause interference to wlan operating in ___ frequency band

Back 339

UNII -3

Front 340

Wi-Fi radios that operates in UNII frequency bands

Back 340

802.11a

802.11n(HT)

802.11 ac(VHT)

Front 341

UNII bands

Back 341

UNII 1: 5.150 - 5.250, 4 channels of 20MHz width, total 100MHz wide

UNII 2: 5.250 - 5.350, 4 channels of 20MHz width, total 100MHz wide

UNII 2 Extended: 5.47 - 5.725, 12 channels of 20MHz width, total 255 MHz wide, 144 channel introduced

UNII 3: 5.725 - 5.850, 5 channels of 20MHz width, total 125 MHZ wide, 165 channel introduced

Front 342

Devices operate sin UNII2 and UNII2 extended should support ___ to avoid radar interference

Back 342

DFS

Front 343

FCC approved 195 MHz of frequency in UNII bands. These new bands are__

Back 343

UNII 2B: 5.35 - 5.47, 120 MHz wide

UNII 4: 5.85 - 5.925, 75 MHz wide

Front 344

Future UNII bands

Back 344

UNII 1 : 5.150 - 5.250 (100 MHz), 4 channels

UNII 2A: 5.250 - 5.350 (100 MHz), 5 channels

UNII 2B: 5.350 - 5.470 (120 MHz), 6 channels

UNII 2C: 5.470 - 5.725 (255 MHz), 13 channels

UNII 3 : 5.725 - 5.850 (125 MHz), 5 channels

UNII 4 : 5.850 - 5.925 (75MHz), 4 channels

Front 345

UNII 2A and UNII 2c would gain extra one channel if FCC approves the future UNII proposal

Back 345

Statement: UNII bands

UNII 2A: 5 channels

UNII 2C: 13 channels

Front 346

The band licensed exclusively for public safety

Back 346

4.94 - 4.99 GHz

Front 347

WiGig operates in __GHz frequency

Back 347

60GHz

Front 348

Maximum theoretical bandwidth of WiGig

Back 348

7Gbps

Front 349

Radios which supports 2.4,5,60 GHz are called __

Back 349

triband radios

Front 350

2 types of RF transmission methods

Back 350

1. Narrow band

2. Spread spectrum

Front 351

Out of two transmission methods narrowband and spread spectrum, which one ill use more bandwidth

Back 351

spread spectrum

Front 352

Out of two transmission methods narrowband and spread spectrum, which one ill use more power

Back 352

narrow band

Front 353

Out of two transmission methods narrowband and spread spectrum, which one is more intended to be affected by RF jammers, interferences

Back 353

narrow band

Front 354

AM and FM are examples of ___ type of transmisson

Back 354

narrow band

Front 355

The phenomenon in which same signal arrives the signal at different times is called

Back 355

multipath

Front 356

A typical delay spread in an indoor wlan environment

Back 356

30 - 270ns

Front 357

Spread spectrum spread their signals across a range of frequencies.Because of this reason they are less affected by multipath. True or False

Back 357

True

Front 358

According 802.11 vendors, required delay spread for 802.11 b is

Back 358

65ns

Front 359

According 802.11 vendors, required delay spread for 802.11 g is

Back 359

150ns

Front 360

802.11 FHSS would use 79 MHz of frequency from __GHz to __GHz

Back 360

2.402 to 2.480

Front 361

Terms used in FHSS

1. Dwell time

2. Hop time

3. Hop sequence

Back 361

Statement: FHSS

Front 362

FHSS transmits data using specific set of frequency for sometime and then switches to another set of frequency. This specific set of frequency is known as

Back 362

Dwell time

Front 363

Time required by the FHSS transmitter to change from one frequency to another is known as

Back 363

Hop time

Front 364

FHSS radio transmits data on a sequence of subchannelscalled hops instead of sending in a finite channel. These set of hops will be repeated and is known as

Back 364

hopping sequence

Front 365

802.11 standard defines hoping sequence can be configured in AP and can be delivered to client using Beacon frames

Back 365

Statement: FHSS

Front 366

As per 802.11 standard hopping sequence must consist of at least 75 frequencies, 1 MHz wide

Back 366

Statement: FHSS

Front 367

Longer the dwell time shorter will be the throughput. True or False

Back 367

False

Note:

If dwell time is lesser transmitter as to hop more and thereby decrease throughput. So longer the dwell time, the greater the throughput.

Front 368

FHSS hop sequence consisting of 75 hops and dwell time of 400ms it would take 30s to complete a hop sequence

Back 368

Statement: FHSS

Front 369

Modulation used by FHSS

Back 369

GFSK Gaussian frequency shift keying

Front 370

The process of converting single data bit into series of bits is known as

Back 370

chipping or spreading

Front 371

802.11 b uses Barker code and CCK for encoding

Back 371

Statement: 802.11 b

Barker code uses 8 bit PN

CCK can encode 4 bits of data with 8 chips which results in 5.5 Mbps

CCK can encode 8 bits of data with 8 chips which results in 11 Mbps

Front 372

Modulation used in 802.11 b

Back 372

DBPSK

DQPSK

Front 373

Data rates supported by PBCC

Back 373

5.5, 11, 22, 33

Front 374

OFDM is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carrier signals are used to carry data on several parallel data streams or channels. Each subcarrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase-shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth

Back 374

Statement: OFDM

Front 375

Out of OFDM, FHSS, DSSS which one is more resistant to negative effects of multipath

Back 375

OFDM

Front 376

Frequency of subcarrier in OFDM

Back 376

312.5KHz

Front 377

Modulation schemes used by OFDM

Back 377

BPSK, QPSK, 16QAM, 64QAM, 256QAM

Front 378

Number of channels available in 2.4GHz band

Back 378

14

For US 1-11

Front 379

Each channel in 2.4GHz ISM band is ___MHz wide

Back 379

22

Front 380

In 2.4GHz what is the conditions to be met if two channels are nonoverlapping

Back 380

Difference between their center frequency should be at least 25 MHz or separated by 5 channels

Front 381

Non overlapping channels in 2.4GHz ISM band

Back 381

1, 6 and 11

Front 382

Access points should be kep 5 to 10 feet separate, so that interference from sideband frequencies does not occur

Back 382

Statement: 2.4GHz Interference

Front 383

Terminal Doppler weather radar(TDWR) operates in which channel

Back 383

120, 124, 128 of UNII 2 extended

Front 384

Non overlapping channels requirement:

1. DSSS- 30 MHz separation between center freq

2. OFDM(a/g)- 25 MHz separation between center freq

3. OFDM(n/ac)- 20 MHz separation between center freq

Back 384

Statement: Non overlapping channels

Front 385

When using 11n/ac aggregate throughput = 65% of data rate. Medium contention eats up 35% of bandwidth

Back 385

Statement: Throughput vs bandwidth

Front 386

When using a/b/g aggregate throughput = 50% of data rate. Medium contention eats up 50% of bandwidth

Back 386

Statement: Throughput vs bandwidth

Front 387

Chapter 7 essentials

Back 387

1. Wireless topologies: WWAN, WLAN, WPAN, WMAN

2. Four types of 802.11 service sets: BSS, ESS,IBSS,MBSS

3. Various way in which 802.11 radios can be used: Indoor/outdoor

4. Purpose of DS: WDS, Distribution system services, Distribution system medium

5. Know about SSID, BSSID, ESSID

6. Various way in which ESS can be designed and their purpose

7. Different configuration modes of AP and client

Front 388

4 types of wireless networking topologies

Back 388

1. WWAN

2. WMAN

3. WLAN

4. WPAN

Front 389

Internet is an example for which networking topology

Back 389

WAN

Front 390

Wi-max is an example for which wireless networking topology

Back 390

WMAN

Front 391

Apple air drop, wifi p2p connections are examples for ___ wireless networking topology

Back 391

WPAN

Front 392

Four 802.11 topologies defined by IEEE standard

Back 392

BSS, ESS, IBSS, MBSS

Front 393

802.11 wireless networks are half-duplex communications

Back 393

Statement: 802.11 communication nature

Front 394

IEEE 802.3 networks are full-duplex communication

Back 394

Statement: 802.3 communication nature

Front 395

Standalone APs are called autonomous APs and controller based APs are called ___

Back 395

lightweight APs or thin APs

Front 396

when a client successfully establish a layer 2 connection with an AP, it is said to be associated with that AP. True or False

Back 396

True

Front 397

Two components of a DS

Back 397

1. Distribution system medium

2. Distribution system services

Front 398

Logical physical medium used to connect AP is called __

Back 398

Distribution system medium

Front 399

802.3 ethernet is an example for ___

Back 399

Distribution system medium

Front 400

Software inside AP which provide switch like intelligence

Back 400

Statement: Distribution system services

Front 401

Wireless bridge, repeaters, mesh networks are examples for ___

Back 401

WDS

Front 402

The 802.11 communications betweenthe repeater and the access point is a WDS. True or False

Back 402

True

Front 403

1. AP and Repeater must be on the same channel

2. There must be 50% cell overlap so that AP and repeater can communicate each other

Back 403

Statement: Repeater requirements

Front 404

Throughput degrades in repeater environment because

1. In a repeater environment, same frame has to be sent twice. client->repeater->AP and vice versa.

2. AP and repeater cell are on the same channel all radios should contend for the medium.

Back 404

Statement: Repeater

Front 405

SSID can be 32 characters long and are case sensitive

Back 405

Statement: SSID

Front 406

SSID stands for

Back 406

Service Set Identifier

Front 407

In a BSS if client stations want to communicate with each other, communication has to go thru AP

Back 407

Statement: BSS

Note:

If client stations support Wi-Fi direct they can directly connect and communicate without the need of an AP

Front 408

BSSID is the MAC address of the radio network interface card of the access point

Back 408

Statement: BSSID

Front 409

BSSID stands for

Back 409

Basic service set identifier

Front 410

Physical coverage provided by an AP in BSS is called ___

Back 410

Basic service area

Front 411

a collection of multiple access points and their associated clients united by single DSM(Distribution system medium) is called

Back 411

ESS

Front 412

In an ESS all APs will have same ssid with overlapping coverage cells to provide seamless roaming. This ssid in an ESS is called

Back 412

ESSID

Front 413

IBSS is also known as peer-to-peer network or adhoc network

Back 413

Statement: IBSS

Front 414

1. In an IBSS first all the client stations should be on the same channel

2. Entire group will have a single SSID WLAN name

3. BSSID will be a virtual mac address generated by first client station which initiates IBSS

Back 414

Statement: IBSS

Front 415

Mesh functions are used to provide wireless distribution of network traffic when wired network is not a good option. The set of APs that provide mesh distribution forms a MBSS

Back 415

Statement: MBSS

Front 416

One or more mesh AP will be connected to wired infrastructure. These mesh Aps are known as

Back 416

mpp(mesh point portal) or mesh root or gateway

Front 417

The other APs which are not connected to wired network will form wireless backhaul connections to MPP to reach wired network. These APs are known as

Back 417

MPs or mesh points

Front 418

Client stations will associate with MPs and the MPs forward their traffic to wired network thru backhaul connections

Back 418

Statement: Mesh networks

Front 419

Generally MBSS uses __GHz for backhaul connections

Back 419

5GHz

Front 420

Mesh routing is based on hardware address and not ip address.

Back 420

Statement: Mesh networks

Front 421

Default path selection protocol to MBSS

Back 421

Hybrid Wireless Mesh Protocol(HWMP)

Front 422

AP configuration modes

Back 422

1. Root

2. Bridge

3. Workgroup bridge

4. Repeater

5. Scanner

6.Mesh

Front 423

Client station modes

Back 423

1. Infrastructure mode

2. Adhoc mode

Front 424

Chapter 8 essentials

Back 424

1. CSMA/CA, physical carrier sense, virtual carrier sense, random backoff timer, IFS,

2. DCF,PCF,HCF

3. WMM, Block Ack

4. Airtime fairness

Front 425

Name the 2 commonly used contention methods used in networks

Back 425

CSMA/CA, CSMA/CD

Front 426

Medium contention used in 802.3 networks

Back 426

CSMA/CD

Front 427

Medium contention used in 802.11 networks

Back 427

CSMA/CA

Front 428

Wired network is duplex communication. It can transmit/receive at same time. If collision occurs wired medium can detect collision and prevent that node from transmitting.

Wireless network is half duplex communication. It can either transmit or receive at that given time. If collision occurs, wireless clients cannot detect it during transmission

Back 428

Statement: why CSMA/CA over CSMA/CD

Front 429

CSMA CA:

CS- determines whether medium is busy or not

MA-ensures every radio gets fair amount of time to transmit

CA-ensures only one radio transmit at any given time

Back 429

Statement: CSMA CA overview

Front 430

In 802.11 communications, every unicast frame is acknowledged

Back 430

Statement: Ack

Front 431

Delivery of aggregated unicast frames is verified using Block Ack

Back 431

Statement: Block Ack

Front 432

Broadcast and multicast frames are never acknowledged

Back 432

Statement: BC/MC frame delivery verification

Front 433

Out of DCF, PCF, HCF which one is mandatory access method for 802.11 communication

Back 433

DCF Distributed coordination function

Front 434

Which channel access method got introduced as part of 802.11e

Back 434

HCF hybrid coordination function

Front 435

Optional channel access method defined in 802.11 standard

Back 435

PCF point coordination function

Front 436

Every 802.11 radio will stay idle for sometime after each transmission to avoid interference and to add/control prioritize frame transmission . This idle period is known as

Back 436

Interframe space a.k.a IFS

Front 437

Six different types of IFS

Back 437

RIFS

Front 438

IFS used for corrupted frames

Back 438

EIFS

Front 439

IFS used for QoS transmission

Back 439

AIFS

Front 440

DIFS = SIFS + 2 * SLOT TIME

SIFS = 10μS for 2.4GHz b/g/n

16μS for 5GHz a/n/ac

SLOT TIME

9μS for OFDM

20μS for 2.4GHz legacy and 2.4GHz b/g/n with long preamble

Back 440

Statement: DIFS

Front 441

Value of Duration/ID field ranges from

Back 441

0 to 32767

Length of Duration/ID field is 2 bytes.

2 bytes = 16bits = 2^15 = 32768

Front 442

Duration/ID of an ACK frame

Back 442

zero

Front 443

Special occasion in which Duration field represents client association id (AID ) instead of transmission time.

Back 443

PS-Poll frame during legacy power management

Front 444

Two collision avoidance defense mechanism used by CSMA/CA

Back 444

Virtual carrier sense

physical carrier sense

Front 445

Layer 1 defense mechanism used by CSMA/CA

Back 445

physical carrier sense

Front 446

Layer 2 defense mechanism used by CSMA/CA

Back 446

Virtual carrier sense

Front 447

PCF will not work for ad hoc networks and will only work in BSS . True or False

Back 447

True

Note:

PCF requires a point coordinator to poll the clients. Since there is no AP present in ad hoc networks PCF will not work

Front 448

For PCF to work only AP is required to support PCF. True or False

Back 448

False

Note:

Both AP and client should support PCF

Front 449

HCF combines DCF and PCF and add enhancements to create two new channel access methods called

Back 449

EDCA, Enhanced distributed channel access

HCCA, HCF controlled channel access

Front 450

TXOP stands for

Back 450

Transmit opportunity

Front 451

IFS used in TXOP

Back 451

SIFS

Front 452

In DCF 802.11 radios can send a single frame after contention and to send another frame they have to contend again. In HCF 802.11 radios can send multiple frames in an allotted time called TXOP

Back 452

Statement:HCF vs DCF

Front 453

Four access categories defined in EDCA

Back 453

Voice AC_VO

Video AC_VI

Best effort AC_BE

Background AC_BK

Front 454

Block Ack is first introduced in ___ amendment

Back 454

802.11 e

Front 455

Two types of Block Ack

Back 455

Immediated and Delayed

Front 456

After sending a block of unicast QoS data frames, transmitter will send a BlockAckReq frame to the receiver. Once the reciever recieves BlockAckreq frame it replies back with BlockAck frame containing delivery status of all the unicast QoS frames . This type of Block Ack is called

Back 456

Immediate Block ACK

Front 457

WMM uses which channel access method of 802.11 e amendment

Back 457

EDCA

Front 458

AC_VO :7,6

AC_VI :5,4

AC_BE :0,3

AC_BK :1,2

Back 458

Statement: Access categories and their priority number

Front 459

Certifications provided by Wi-Fi alliance for testing QoS

Back 459

WMM

WMM-POWER SAVE

WMM ADMISSION CONTROL

Front 460

Airtime fairness is introduced to prevent slower devices from bogging down the rest ofthe network. True or False

Back 460

True

Front 461

Chapter 9 essentials

Back 461

1. 802.11 MAC architecture

2. MSDU, MPDU, PSDU, PPDU

3. Differences and similarities b/w 802.3 and 802.11 frames

4. Control,Management, Data frames

5. Active scanning/Passive scanning

6. Authentication,DeAuthentication Association,ReAssociation,DisAssociation,Roaming,Ack Frame

7. Fragmentation

8. Protection mechanisms RTS/CTS, CTS-to_Self

9. Power management : TIM, DTIM, ATIM, WMM-PS, UAPSD, Legacy PS, 802.11n PS

Front 462

Two sublayers of Data link layer

Back 462

1. Logical Link Control(LLC) sublayer

2. Media Access Control(MAC) sublayer

Front 463

MSDU contains payload from layers __

Back 463

3 to 7

Front 464

Datagram n MAC sublayer is known as

Back 464

MPDU(MAC Protocol Data Unit)

Front 465

Contents of MPDU

Back 465

MAC header + Frame body + FCS

Front 466

Sublayers in PHY layer

Back 466

1. PLCP(Physical Layer Convergence Procedure) sublayer

2. PMD(Physical Medium Dependent) sublayer

Front 467

When MPDU reaches PLCP sublayer, it is known as

Back 467

PSDU PLCP Service Data Unit

Front 468

PLCP sublayer adds PHY header and preamble to PSDU. The resulting datagram is called

Back 468

PPDU PLCP Protocol Data Unit

Front 469

Preamble in PPDU is used for

Back 469

synchronization b/w transmitting and receiving 802.11 radios

Front 470

PMD sublayer takes the PPDU, modulates and transmit the bits

Back 470

Statement: PMD function

Front 471

Maximum size of 802.3 frame

Back 471

1518 bytes with data payload 1500 bytes

1522 bytes with data payload 1504 if VLAN information is present

Front 472

Maximum size of IP packets based on MTUs

Back 472

1500 bytes

Front 473

802.11 MAC header has 4 address fields

Back 473

Statement: 802.11 address

Front 474

Size of MAC address is

Back 474

6 bytes = 6 octets = 48 bits

Front 475

First 3 octets of MAC address represent ___

Back 475

OUI Organizationally Unique Identifier

in other words vendor name like Intel, Broadcom, Marvell

Front 476

Last 3 octets of MAC address represent

Back 476

NIC specific information

Front 477

3 major 802.11 frame types

Back 477

1. Control

2. Management

3. Data

Front 478

Out of 3 frame types, control management and data, which frame type is used by 802.11 radios to join or leave a BSS

Back 478

Management frames

Front 479

Management frames are also known as

Back 479

MMPDU MAC Protocol Data Unit

Front 480

Management frames does not carry any upper layer data. True or False

Back 480

True

Front 481

(Re)Assoc req/res

Auth re/res

DeAuth

Probe req/res

Beacon

ATIM

ACTION

ACTION No ACK

Timing advertisement

Back 481

Management frames

Front 482

Control frames responsible for clear the channel, acquire the channel and provide unicast frame acknowledgement

Back 482

Statement: Control frames

Front 483

RTS/CTS,CTS-to-SELF

ACK,Block Ack, Block Ack Req

PS-POLL, Control wrapper

Back 483

Control frames

Front 484

Any data frames that does not carry upper layer information are unencrypted. True or False

Back 484

True

Front 485

Information present in Beacon frames

Back 485

time stamp, spread spectrum parameter, channel information, data rates, service set capabilities,ssid, tim, rsn information, wmm, vendor info

Front 486

2 types of scanning

Back 486

active and passive

Front 487

In __ client listens to beacons sent by the AP

Back 487

passive

Front 488

In __ client sents probe request in all the available channels and collect APs in the vicnity

Back 488

active

Front 489

A probe request with null ssid length is called

Back 489

null probe request

Front 490

A probe request with a specic ssid name is called

Back 490

directed probe req

Front 491

2 types of authentication

Back 491

Open system authentication

Shared key authentication

Front 492

AID is present in which frame

Back 492

Association response

Front 493

In order for a client station to successfully associate to an AP basic rates of AP and STA should match

Back 493

Statement: Basic rates

Front 494

Basic rates are required rates for a STA who wants to join the BSS. If client station does not support all the basic rates of AP , it won't be able to associate to that AP

Supported rates are data rates that AP offers to a client station, but the client does not have to support all of them

Back 494

Statement: Basic vs Supported rates

Front 495

Ability for the client station to transition from one Ap to another by maintaining upper layer connectivity is called __

Back 495

Roaming

Front 496

Roaming decision is made by __

Back 496

client station

Front 497

1. DisAssociation and DeAuthentication are notification and not request

2. Client or AP any device can send DisAssoc and DeAuth

3. Both DisAssoc and DeAuth cannot be refused by either party except 802.11w in negotiated and MIC fails

Back 497

Statement: DisAssoc and DeAuth

Front 498

1.In 802.11 every unicast frame is acknowledged

2. Ack is used for successful delivery verification

3. Receiving STA copies MAC address of transmitting STA from the data frame and places in the RA field of ACK frame. When the transmitting STA receives ACK frame with its MAC address in RA field it confirms successful delivery of frame

Back 498

Statement: ACK

Front 499

Size of ACK frame

Back 499

14 bytes = 14 octets

2 byte FC +2 byte Duration+6 byte RA + 4 byte FCS

Front 500

Fragmentation is used increase network performance when there is increased data corruption. True or False

Back 500

True

Front 501

Suppose an AP is configured in 802.11b mode. What types of client devices can associate the the AP

Back 501

802.11 DSSS, 802.11b HR-DSSS, 802.11g ERP-DSSS, 802.11n

using the data rates 1, 2, 5.5, 11

Front 502

802.11 g mode is also known as

Back 502

Pure G network

Front 503

Suppose an AP is configured in 802.11g mode. What types of client devices can associate the the AP

Back 503

802.11 g ERP-OFDM, 802.11n using data rates

6,9,12,18,24,36,48,54

Front 504

Suppose an AP is configured in 802.11bg mixed mode. What types of client devices can associate the the AP

Back 504

802.11 DSSS,802.11 b, 802.11g, 802.11n

Front 505

In a BG mixed mode environment, the transmitting 802.11 radio will send a RTS/CTS or CTS-to-Self before transmission. Out of legacy/b/g radios which STA will will send RTS before transmission and at what rate?

Back 505

802.11g STA will send RTS/CTS or CTS-to-Self at basic rates in which other clients like 802.11 DSSS/802.11b devices understand

Front 506

ERP protection is triggered when

Back 506

1. When an non-ERP STA associate to ERP AP

2. When ERP AP hears a beacon frame from another AP whose supported data rates contain only 802.11 b or 802.11 DSSS rates

3. When ERP AP hears a management frame (other than probe req)where the supported rates include only 802.11 b or 802.11 DSS rates

Front 507

802.11g radios revert to 802.11b data rates when the protection mechanism is used. True or False

Back 507

False

Note:

802.11 g radios transmit at higher 802.11 ERP OFDM rates itself

Front 508

Duration of RTS

Back 508

CTS+DATA+ACK+3SIFS

Front 509

Duration of CTS

Back 509

DATA+ACK+2SIFS

Front 510

CTS-to-Self is commonly used by AP. True or False

Back 510

True

Front 511

NULL function frame or NULL Data frame is commonly used

Back 511

power management

Front 512

Beacons are transmitted at consistent predetermined interval known as

Back 512

Target Beacon Transmission Time(TBTT)

Front 513

A DTIM is used to ensure all the client stations in power saving mode are awake during multicast/broadcast transmission

Back 513

Statement: DTIM

Front 514

A DTIM interval o f 3 means every 3rd beacon will be a DTIM beacon

A DTIM interval o f 1 means every beacon is a DTIM beacon

Back 514

Statement: DTIM

Front 515

A DTIM value of 0 indicates current TIM is a DTIM

Back 515

Statement: DTIM

Front 516

ATIM is a frame used for power management by adhoc clients.

TIM is field in Beacon

Back 516

Statement: TIM vs ATIm

Front 517

Disadvantages of legacy powersave

Back 517

1. Amount of client station dozing is determined by client driver not application traffic

2. Client has to wait for a Beacon frame with its TIM field set to download unicast buffered frames intended to it

3. Client has to send PS-POLL frame to retrieve every single buffered frame

These caused time sensitive application like voip to decreased performance

Front 518

Advantages of WMM-PS

Back 518

1. Application sets client dozing behaviour and not client's driver

2. Client can download buffered frame by sending a trigger frame and does not have to wait for Beacon frame

3. Trigger frame can be any frame, can be a data frame also thereby avoiding PS-POLL frame

4. All the buffered frames are send in frame burst during the allocated TXOP

Front 519

2 types of Automatic powersave delivery

Back 519

Static A-PSD S-APSD

Unscheduled A-PSD U-APSD

Front 520

Powersave feature introduced in 802.11n

Back 520

SM power save, PSMP

Front 521

Chapter 10 essentials

Back 521

1. 802.11 radio form factors, radio chipsets, client utilities: enterprise, integrated and third party

2. Logical network planes of operation and where they are used: Management, control , data planes

3. WLAN architecture: Autonomous, Centralized and Distributed

4. WLAN specialty architecture

Front 522

Different types of 802.11 radio formafactors

Back 522

external:

PCMCIA, Express card, USB

Internal:

mini PCIE, PCIE Express, Embedded

Front 523

3 types of client utilities

Back 523

1. Integrated operating system client utilities

2. Vendor specific

eg: Intel PROSet wireless client interface

3. Third party

Front 524

Juniper Networks Odyssey Access Client is an example for ___ type of client utility

Back 524

third party

Front 525

3 logical planes of operation in networking

Back 525

1. Management plane

2. Control plane

3. Data plane

Front 526

Management plane: N/w monitoring

Control plane: N/w intelligence

Data plane: location where user traffic forwarded

Back 526

Statement: planes of operation

Front 527

Network management solution to monitor routers and switches is an example __ plane

Back 527

Management

Front 528

Dynamic layer 3 protocols like OSPF, BGP used in routers and CAM tables , Spanning tree protocol used in switches to forward packets is an example for ___ plane

Back 528

control

Front 529

In an Autonomous AP, all the three planes exist in AP itself. True or False

Back 529

True

Front 530

Functions of Management plane

Back 530

1. WLAN configuration: SSID, security, power settings, wmm

2. WLAN monitoring and reporting: Statistics like number of clients (re)associated, ACKS ,data rates

3. WLAN firmware management: firmware upgrade

Inshort all the administrative activities :-)

Front 531

Functions of Control plane

Back 531

1. Dynamic RF or Radio resource Management(RRM): Coordinated channel and power setting for multiple APs

2. Roaming mechanism

3. Client load balancing:collecting and sharing client load and performance metrics b/w multiple APs to improve overall WLAN operation

4. Mesh protocols

Front 532

3 types of WLAN architecture

Back 532

1. Autonomous

2. Centralized

3. Distributed

Front 533

Standalone APs are also known as

Back 533

Autonomous APs or fat APs

Front 534

BVI is

Back 534

Bridged virtual interface

Front 535

BVI is the management interface for an AP

Back 535

Statement: BVI

Front 536

SNMP,CAPWAP are mostly used management protocol to manage and monitor network in NMS. True or False

Back 536

True

Front 537

Autonomous APs are deployed at access layer and typically powered by PoE.

The integration service in Autonomous AP translates 802.11 frame to 802. 3 frame

Back 537

Statement: Autonomous AP

Front 538

NMS is a management plane solution. No control plane and data plane mechanisms exist in NMS.

Back 538

Statement : NMS

Front 539

3 layers in hierarchical internetworking model

Back 539

1. Access layer

2. Distribution layer

3. Core layer

Front 540

NMS solutions deployed at company data center are referred as on premise NMS

NMS solutions are available in cloud as software subscription service

Back 540

Statement : NMS

Front 541

2 types of cloud networking models

Back 541

1. Cloud-Enabled networking(CEN)

2. Cloud-Based networking(CBN)

Front 542

In Cloud-Enabled networking(CEN), management plane resides in the cloud . Data plane mechanisms will be present locally in hardware

Back 542

Statement: CEN

Front 543

In Cloud-Based networking(CBN), both management and data plane resides in the cloud

Back 543

Statement: CBN

Front 544

In centralized WLAN architecture all the logical planes management, control, data resides in WLAN Controller. True or False

Back 544

True

Front 545

CAPWAP is

Back 545

Control and Provisioning of Wireless Access Points

Front 546

CAPWAP is a WLAN ___ protocol

Back 546

management

Note:

CAPWAP protocol can also be used for tunneling user traffic

Front 547

In centralized wlan architecture integration service resides in

Back 547

WLAN controller

Front 548

Controller based access points are also known as

Back 548

lightweight APs or thin Aps

Front 549

WLAN controller is deployed at __ layer of internetworking model

Back 549

core

Front 550

Lightweight APs are deployed at __ layer of internetworking model

Back 550

access

Front 551

Lightweight APs are powered using __

Back 551

PoE provided

Front 552

Lightweight APs tunnel all the traffic to WLAN controller. Integration service inside the controller converts 802.11 frame into 802.3 format and Distribution System Service(DSS) directs the traffic to wired destination

Back 552

Statement: WLAN controller

Front 553

AP group profile:

Channel, Supported data rates, txpower configurations

Back 553

Statement: AP group profile

Front 554

WLAN group profile:

SSID, security, VLAN, QoS configurations

Back 554

Statement: WLAN group profile

Front 555

An AP can be only in one AP group profile but can be in multiple WLAN profile. True or False

Back 555

True

Front 556

SSID is logical name and BSSID is MAC address of the 802.11 radio

Back 556

Statement: SSID vs BSSID

Front 557

WLAN can create multiple SSIDs and BSSIDs. True or False

Back 557

False

Front 558

WLAN Controller features

Back 558

1. AP management

2. 802.11 traffic tunneling

3. AP group profile

4. WLAN group profile

5. Multiple BSSIDs

6. VLAN

7. User management

8. Layer 2 security

9. Layer 3 VPN concentrator

10. Captive portal

11. Automatic failover recovery and load balancing

12. Internal WIDS

13. Firewall capabilities

14. Bandwidth management

15. PoE

16. Layer3 roaming

17. Management interface

18. Dynamic RF

Front 559

In split mac architecture, control and management frames are not tunneled to wlan controller since they doesn't have any upper layer payloads and DSS doesn't have to translate to 802.3 frames.

Back 559

Statement: split mac architecture

Front 560

CAPWAP protocol define split mac architecture. True or False

Back 560

True

Front 561

CAPWAP is proposed by

Back 561

Internet Engineering Task Force(IETF)

Front 562

2 types of controller data forwarding models

Back 562

1. Centralized data forwarding

2. Distributed data forwarding

Front 563

In centralized data forwarding AP tunnels every 802.11 user data traffic to controller or come from controller. AP plays a passive role in data handling

Back 563

Statement: Centralized data forwarding

Front 564

In Distributed data forwarding AP solely determines where and how to forward user data traffic. Controller plays a passive role in Distributed data forwarding.

Back 564

Statement: Distributed data forwarding

Front 565

One major disadvantage of Distributed data forwarding is control plane mechanisms like Dynamic RF, Layer 3 roaming, Firewall policy enforcement, Fast secure roaming will not be available

Back 565

Statement: Distributed data forwarding

Front 566

Remote office wlan controller less powerful and less expensive than core wlan controller. True or False

Back 566

True

Front 567

Remote office wlan controller is used to manage local APs in remote office branches. True or False

Back 567

True

Front 568

Remote office wlan controller connects with core wlan controller thru a secure WAN link using VPN and download all the configuration data to manage local APs

Back 568

Statement: Remote office wlan controller

Front 569

Distributed WLAN Architecture:

No WLAN Controller present.

All control plane and data forwarding intelligence resides in AP

APs share control plane info b/w them using proprietary protocols

Management plane is centralized usually a local or cloud NMS server

Back 569

Statement: Distributed WLAN Architecture

Front 570

VLANs will be configured at the core layer s/w in wlan controller based architecture and APs will be connected to the accessport of access layer s/w

VLANS will be configured at the access layer s/w , and APs will be connected to 802.1Q trunk port of the access layer s/w

Back 570

Statement: VLAN config in controller based vs distributed

Front 571

WLAN architecture in which wlan controller capabilities are integrated into wired devices like routers, switches is known as

Back 571

Unified WLAN Architecture

Front 572

A device which provides wireless connectivity to the wired infrastructure devices which do not have radio cards is called ___

Back 572

Workgroup Bridge(WBG)

Front 573

All the wired infrastructure devices will be connected to WGB.

WGB connects to an AP and provide wireless connectivity to these wired devices which do not have a radio card

small desktop workgroups, cash registers, network printers are few devices which we can connect ot WGB

Back 573

Statement: WGB

Front 574

Wired devices connected to WGB can contend the half-duplex medium. True or False

Back 574

False

Front 575

WGB can also provide wireless connectivity just like AP to other wireless client stations. True or False

Back 575

False

Front 576

A device used to connect one or more wired devices together wirelessly

wired device----wireless bridge---wired device

Back 576

wireless bridge

Front 577

Wireless bridge posess all the features that an Autonomous Ap has. True or False

Back 577

True

Front 578

A wireless bridge is usually used as redundant backup to T1 or fiber connections between buildings

Back 578

Statement: Wireless bridge

Front 579

A wireless bridge link that connects only 2 wired networks using 2 bridges are known as

Back 579

point-to-point bridge(PtP)

Front 580

In PtP bridge, one bridge will be root bridge and other will be non root bridge

Back 580

Statement: point-to-point bridge(PtP)

Front 581

A bridge link that connects multiple wired networks are known as

Back 581

point to multipoint bridge(PtMP)

Front 582

In PtMP bridge link, one bridge will be root bridge and all other bridge will be non root bridge.

All the non root bridge connects to root bridge

Back 582

Statement: point to multipoint bridge(PtMP)

Front 583

In PtMP bridge link, for redundancy there can be more than one root bridge. True or False

Back 583

False

Note: Only one root bridge is possibel

Front 584

Root bridge will have high gain omni directional antenna and non root bridges will have uni directional antenna pointing back to root bridge. True or False

Back 584

True

Front 585

Vendor bridge configuration modes

Back 585

1. WGB

2. Root with clients

3. Root without clients

4. Non root with clients

5. Non root without clients

Front 586

Associating clients to bridge will reduce throughput. True or False

Back 586

True

Front 587

Its is a recommended bridge deployment practice to use two bridge links as opposed to repeating the link of a root bridge to non root bridge. True or False

Back 587

True

Front 588

Things to be considered while deploying a bridge link

Back 588

Fresnel zone

Earth bulge

Free space path loss

Fade margin

IR and EIRP values by regulatory authority

Front 589

In long distance link, ACK timeout setting are adjusted so that delayed arrival of ACK for unicast frame can be accommodated thereby preventing retransmission of a frame that does not need to be resent and improving network performance.

Back 589

Statement: long distance bridge link

Front 590

Retransmission of a frame that does not need to be resent due to ACK timeout degrade throughput by 50%. True or False

Back 590

True

Front 591

WLAN routers are almost like home routers but with a better hardware quality and few extra features

Access points have bridged virtual interface whereas WLAN routers have separate routed interface.

Radio card of WLAN routers exists in one subnet and WAN port exists on a different subnet

Back 591

APs Vs WLAN routers

Front 592

Wireless Mesh APs communicate with each other using proprietary layer 2 protocols and create self forming and self healing wireless infrastructure over which edge devices can communicate

Back 592

Statement: Mesh

Front 593

Routing of data traffic in Mesh networks are based on measurement of traffic, signal strength, data rates hops

Back 593

Statement: Mesh

Front 594

Mesh n/w use 5GHz to communicate with each other and 2.4GHz to provide client connections

Back 594

Statement: Mesh

Front 595

WLAN array is an all in one device, which combines multiple APs, wlan controller with sectorized antennas to provide 360 degree coverage

Back 595

Statement: WLAN array

Front 596

Vendor which provides WLAN array solution

Back 596

Xirrus

Front 597

WLAN arrays can be deployed where less hardware is needed,high density areas

Back 597

Statement: WLAN array

Front 598

WLAN array can combine upto 16APs

Back 598

Statement: WLAN array

Front 599

A 16 access-point WLANarray would consist of four 2.4 GHz radios and twelve 5 GHz radios.One of the radios can beused as a full-time sensor device for the WIDS that is embedded with the controller

Back 599

Statement: WLAN array

Front 600

WLAN solution in which multiple access points share a single BSSID

Back 600

Virtual AP system

Front 601

In Virtual AP system, BSSID is same for all the APs.When client roams , they think they are connected to same single access point resulting zero roaming handoff time and latency issues will be solved

Back 601

Statement: Virtual AP system

Front 602

All the APs in Virtual AP system uses single channel architecture(only one channel) and contend for the medium in coordinated manner handled by WLAN controller

Back 602

Statement: Virtual AP system

Front 603

Real-Time Location Systems are used to locate devices accurately with Wi-Fi RFID tags

Back 603

Statement: Real-Time Location Systems

Front 604

Infrastructure required for Real-Time Location Systems to function

Back 604

pre-existing WLAN infrastructure, pre-existing WLAN clients,wlan rfid tags, rtls server, rtls sensor

Front 605

Vendors which produce RTLS solutions

Back 605

Aeroscout, Ekahau

Front 606

Essential requirements for VoWiFi setup

Back 606

VoWiFi phone

WMM support

PBX to route the calls to telephone cables

Front 607

In centralized wlan controller model, all the 802.11 user frames are tunnelled to WLAN controller.

WLAN controller are deployed close to core layer

An extra WLAN controller is also placed for redundancy so that if one fails whole WiFi network will not go down

Back 607

Statement: Centralized WLAN architecture

Front 608

Chapter 11 essentials

Back 608

1. WLAN vertical markets

2. FMC Fixed mobile convergence

Front 609

VoWiFi phones have low transmission power to decrease battery usage and increase battery longevity. True or False

Back 609

True

Front 610

Choppy audio in video conference will be highly disruptive, causing participants to ask speaker to repeat whereas if audio is clear and video is choppy participants can understand what speaker has said. This means video has higher loss tolerance than voice. True or False

Back 610

True

Front 611

In most of the use cases video streaming devices are stationary not moving or mobile.

Eg: Video streaming of tv,music,wireless security cameras, video conference

Back 611

Statement: Video

Front 612

Healthcare is biggest users of RTLS technology

Back 612

Statement: RTLS users

Front 613

1. undergroundcable or fiber between the two buildings,

2. high-speed leased data circuit

3. building-to-building wireless bridge

Out of these which one is more cost effective

Back 613

building-to-building wireless bridge

Note:

clear RF line of sight and a technician to setup wireless bridge is all that required

Front 614

School wall are usually made up of cinder block which attenuates 2.4 and 5GHZ RF signals .To provide better coverage, more access points are required while deploying wireless in school environment.

Back 614

Statement: Deploying wireless in school environment

Front 615

Wireless networks deployed in warehouses are designed to provide more coverage than bandwidth. True or False

Back 615

True

Front 616

Most commonly used wireless devices in warehouses are barcode scanners

Back 616

Statement: warehouse wlan deployment

Front 617

Key uses of WLAN in retail environment

Back 617

1. support to operations of the store and retails transactions

2. location tracking of items

3. customer analytics

4. supplementary internet access

Front 618

WLAN vendor who specialize in providing customer analytics

Back 618

Euclid analytics

Front 619

Advantages of using WLAN over wired

Back 619

end user mobility

quick and secure data access

Front 620

Key uses of WLAN in hospital/healthcare environment

Back 620

1. quick,secure access to clinical data, patient or hospital data

2. VoWiFI

3. RTLS

Front 621

Companies recommend their employees to use VPN while they connect to public hotspot or network. The reason behind this

Back 621

hotspots are not secured no matter its free or paid

Front 622

Key uses of WLAN in stadium environment

Back 622

1. high speed internet access to press box

2. video surveillance

3. ticketing

4. point of sale transaction processing

Front 623

Automatic uploading of video surveillance datas to central server is a common use case in WLAN deployment in law enforcement environment

Back 623

Statement: WLAN deployment in law enforcement environment

Front 624

WLAN networks are used a first responder networks during disasters/crisis when regular cellular network fails.

Back 624

Statement: First responder networks

Front 625

Mobile devices which can communicate

using either cellular network or wlan network by switching between them are called

Back 625

Fixed mobile convergence(FMC)devices

Front 626

Consideration to be taken while integrating mobile devices into wlan infrastructure

Back 626

1. ensure devices are capable of connecting to network with proper authentication

2. ensure device support encryption protocols and roam smoothly

3. ensure network access not only based on user identity but also considering device id and connection characteristics

Front 627

When mobile devices with low tx power are integrated to wlan infrastructure, coverage areas are made small to avoid RF dead zones.

Back 627

Statement: Integration of mobile device into WLAN infrastructure

Front 628

Wireless connectivity is least recommended in distribution and core layers. True or False

Back 628

True

Front 629

WLAN is an end user access technology

Back 629

Statement: wireless lan

Front 630

WLAN vertical markets

Back 630

1. Corporate data access and end user mobility

2. Network extension to remote areas

3. Bridging: building to building connectivity

4. Wireless ISP: last mile data delivery

5. SOHO

6. Mobile office networking

7. Branch offices

8. Education/classroom use

9. Industrial: warehouse and manufacturing

10. Retail

11. Healthcare

12. Municipal networks

13. Hotspots

14. Stadium networks

15. Transportation networks

16. Law enforcement networks

17. First responder networks

18. Fixed mobile convergence

Front 631

The goal of fixed mobile convergence is to enable the user to have a singledevice with a single phone number and to enable the user to roam between differentnetworks, taking advantage of the least expensive and best performing network that isavailable.

Back 631

Statement: FMC goal

Front 632

Last mile internet service is provided by

Back 632

1. Cable provider

2. Telecom company

3. WISP

Front 633

PtMP network design is also known as

Back 633

Star or bub and spoke

Front 634

To provide higher throughput and prevent single point of failure, multiple PtP bridges b/w the same locations are usually installed

Back 634

Statement: advantage of multiple PtP bridges

Front 635

key concerns of healthcare providers when installing a wirelessnetwork

Back 635

1. Fast, secure and accurate access to patient data

2. RF interference from other healthcare devices

Front 636

Chapter 18 essentials

Back 636

1. Difference b/w MIMO vs SISO

2. Spatial multiplexing

3. MIMO diversity

4. TxBf

5. 20MHz/40MHz channels

6. Guard interval

7. MCS

8. HT-PPDU formats: non-HT legacy, HT Mixed, HT Greenfield

9. HT MAC Enhancements

10. HT protection modes

Front 637

Maximum theoretical data rate of 802.11n

Back 637

600 Mbps

Front 638

propagation phenomenon in which same signal arriving at receiver at same time or nano second difference by travelling different paths is known as __

Back 638

multipath

Front 639

MIMO is

Back 639

Multiple Input Multiple Output

Front 640

MIMO makes use of positive affects of multipath

Back 640

Statement: MIMO

Front 641

All wifi alliance certified n products must also support WMM and WPA/WPA2 security

Back 641

Statement: wifi certified n

Front 642

Features tested in wifi alliance certification of 802.11 n

Back 642

1. two spatial streams for AP and 1 spatial stream for STA

2. support of 3SS if implemented

3. AMSDU,AMPDU in receive mode. AMPDU in transmit mode

4. BlockACK

5.2.4GHz operation

6. 5GHz operation

7. concurrent operation of 2.4/5 GHz

8. 40 MHz channels on 5GHz

9. 20/40 coexistence

10.SGI for 20/40 MHz

11.Greenfield preamble

12. STBC

13. HT Duplicate mode

Front 643

STBC and CSD are transmit diversity techniques implemented using MIMO. True or False

Back 643

True

Front 644

MRC is ___ diversity techique

Back 644

receive

Front 645

Necessary hardware required to transmit and receive signal processing is called __

Back 645

radio chain

Note:

all of the supporting architecture including mixtures, amplifiers, analog/digital converters

Front 646

Tx X Rx:SS

Eg: 2x3:2

Total 3 radio chains, 2 transmitter, 3 receiver, 2 spatial streams

Eg: 3x3:2

Total 3 radio chains, 3 transmitter, 3 receiver, 2 spatial streams

Back 646

Statement: radio chain denotation

Front 647

Maximum supported radio chain for 802.11n

Back 647

4x4:4

Front 648

Sending multiple streams of uniques data using multiple antennas is known as

Back 648

Spatial multiplexing

Note:

These unique data streams are also known as spatial streams(SS)

Front 649

Most of handheld devices uses 1x1:1 MIMO because increasing radio chain will increase drainage of battery

Back 649

Statement: MIMO radio in handheld devices

Front 650

Antenna diversity(both receive and transmit) is method of using multiple antennas to survive negative effects of multipath

Back 650

Statement: Antenna diversity

Front 651

pre-802.11n devices used __ diversity

Back 651

switched

Front 652

Multiple copies of same signal are received at multiple antennas and signals with best amplitude is choosen and other are ignored.

Back 652

Statement: switched diversity

Front 653

When switched diversity used in transmitting only one antenna will be used out of multiple antennas. The transmitting antenna will be that antenna where best amplitude signal is last heard

Back 653

Statement: switched diversity

Front 654

combining multiple signals by uniquely looking at each signal and adding them in an optimal way using MRC algorithms to raise SNR is known as

Back 654

MRC

Front 655

Sending multiple copies of same data through multiple antennas is known as

Back 655

STBC

Front 656

STBC can be used when number of radio chains exceeds number of spatial stream.

Back 656

Statement: STBC

Front 657

STBC is a transmit diversity. True or False

Back 657

True

Front 658

STBC works with both 11n and legacy devices. True or False

Back 658

False

Front 659

Cyclic shift diversity is a transmit antenna diversity. True or False

Back 659

Statement: True

Front 660

CSD works with both 11n and legacy devices. True or False

Back 660

True

Front 661

TxBF increases SNR and throughput by carefully adjusting phase of the transmitted signals

Back 661

Statement: TxBF

Front 662

TxBF is used when number of radio chains are greater than spatial streams

Back 662

Statement:TxBF

Front 663

TxBF increases range . True or False

Back 663

True

Front 664

In TxBF transmitter will not be sending multiple streams of unique data. Instead it will send multiple copies of same data phase adjusted for each RF signal

Back 664

Statement: TxBF

Front 665

Transmitters while using TxBF will use a implement a feedback mechanism to learn about receiver location using ___ frames

Back 665

sounding

Front 666

TxBF transmitter: Beamformer

TxBF receiver: Beamformee

Back 666

Statement:TxBF

Front 667

2 types of beamforming

Back 667

Implicit feedback

Explicit feedback

Front 668

Implicit feedback: beamformer creates steering matrix

Explicit feedback: beamformee creates steering matrix

Back 668

Statement: TxBF

Front 669

Transmitter send sounding frames and then receives long training symbols send by receiver which allows transmitter to learn about the MIMO channel b/w transmitter and receiver.

Back 669

Statement: Implicit feedback

Front 670

Receiver learns about the channel from the long training symbols sent by the transmitter, calculate steering matrix and send back to the transmitter

Back 670

Statement: Explicit feedback

Front 671

Sonar is an analogy for which type of beamforming

Back 671

Implicit

Front 672

Beamforming is not practically implemented in 802.11n. True or False

Back 672

True

Front 673

Back 673

Statement: subcarriers

Front 674

2.4GHz 40MHz channels are not used in multichannel architecture because two 2.4GHz 40MHz channels overlap.

Back 674

Statement: 40MHz channels

Front 675

2.4GHz 802.11n APs use 20MHz channels by default

Back 675

Statement: 2.4GHz channels

Front 676

An AP using 40MHz channel will be forced to used 20MHz channel if it hears a AP with 40MHz intolerant bit set.

Back 676

Statement: 2.4GHz channels

Front 677

40MHz intolerant is only applicable for 2.4GHz. True or False

Back 677

True

Front 678

Time between symbols that accommodates late arrival of symbols over long paths is known as

Back 678

Guard interval

Front 679

Guard interval prevents __

Back 679

Intersymbol interference

Front 680

Guard interval is 4x times delay spread

Back 680

Statement: Guard interval

Front 681

Delay spread is the time difference b/w multipaths of the same signal

Back 681

Statement: Delay spread

Front 682

Normal delay spread value

Back 682

200ns

Front 683

Legacy GI value

Back 683

800ns

Front 684

802.11n GI value

Back 684

400ns

Front 685

SGI increases throughput by 10%

Back 685

Statement: SGI

Front 686

MCS is

Back 686

Modulation and coding scheme

Front 687

Total MCS rates in 802.11n

Back 687

77

Front 688

Mandatory MCS rates in 802.11n

Back 688

0-7

Front 689

Data rates are based on channel bandwidth, guard interval, spatial streams, modulation, coding method

Back 689

Statement: MCS rates

Front 690

Maximum data rate in 1x1:1 with 800ns GI

Back 690

65Mbps

Front 691

Maximum data rate in 1x1:1 with 400ns GI

Back 691

72Mbps

Front 692

Main purpose of PHY header

Back 692

use signal field

1. to indicate how long it will take to transmit 802.11 frame

2. to notify receiver MCS rates used

Front 693

3 Preambles introduced in 802.11n

Back 693

Snon-HT legacy

HT-mixed

HT-Greenfield

Front 694

Support for non-HT legacy is mandatory in 802.11n and can occur in 20 MHz

Back 694

Statement: Preamble

Front 695

Support for HT-mixed is mandatory in 802.11n

Back 695

Statement: Preamble

Front 696

The length field in the legacy section of HT-mixed header indicate legacy STAs how long medium will be busy.

Back 696

Statement: Preamble

Front 697

Support for HT-Greenfield is optional in 802.11n

Back 697

Statement: Preamble

Front 698

Legacy STA cannot decode HT-Greenfield PPDUs and will interpret as noise

Back 698

Statement: Preamble

Front 699

2 aggregation methods

Back 699

A-MSDU

A-MPDU

Front 700

Frame aggregation is a method of combining multiple frames into a single frame for transmission

Back 700

Statement: aggregation

Front 701

All aggregated frames will have a single MAC header

Individual MSDUs are of same QoS category

All MSDUs will have a single destination

Whole A-MSDU is encrypted by treating it as a single frame

Back 701

Statement: A-MSDU

Front 702

Individual MPDUs will have separate MAC header

Individual MPDUs should be of same Qos category

Individual MPDUs are encrypted seperately

All MPDUs should have same receiver address

Back 702

Statement: A-MPDU

Front 703

AMPDU uses BLOCK ACK and AMSDU uses normal ack

Back 703

Statement: aggregation ack

Front 704

RIFS only works with HT-greenfield

Value of RIFS is 2ms

Back 704

Statement: RIFS

Front 705

Power save supported by 802.11n devices

Back 705

legacy

wmm-ps

SM power save: Static, Dynamic

PSMP: ScheduledPSMP. Unscheduled PSMP

Front 706

802.11n devices power down all the radio chains except one.

802.11n device inform this by sending SM powersave action frames

802.11n device will use the SM powersave action frames to inform AP it powered up all the radio chains

Back 706

Statement: Static SM powersave

Front 707

802.11n devices power down all the radio chains except one after frame exchange.

AP sends an RTS frame when client receives it, it power up all radio chains and respond with CTS

Back 707

Statement: DynamicSM powersave

Front 708

HT protection modes

Back 708

4 modes, 0-3

Front 709

Mode 0-Greenfield (No protection) mode

Mode 1-HT non member protection mode

Mode2-HT 20MHZ protection mode

Mode3-non-HT mixed mode

Back 709

Statement: HT protection modes

Front 710

1. Only associated STA are HT capable

2. If HT BSS is 20MHz all the STA must be 20 MHz capable

3. If the BSS is 20/40MHz , all the STA must be 20/40 capable

Back 710

Statement: Mode 0-Greenfield (No protection) mode

Front 711

1. All the STAs must be HT STAs

2. Protection kicks in when a non member legacy STA or AP is heard by AP

Eg: 802.11 a STA or AP transmitting in 20 MHz space interferes with primary or secondary channel of 40 MHz HT AP

Back 711

Statement: Mode 1-non-member protection mode

Front 712

1. BSS is 20/40 and all STAs are 20/40

2. Protection must be used by 20/40 capable STAs while transmitting at 40MHz when a 20MHz only STA associates to 20/40 BSS

Back 712

Statement: Mode2-HT 20MHz protection mode

Front 713

1. BSS is 20 MHz or 20/40

2. protection kicks in when a legacy STA associates to BSS

3. All the HT STAs uses protection mechanisms before transmitting

Back 713

Statemnt: Mode3 non-HT mixed mode

Front 714

Protection mechanism in which two identical 20 MHz non-HT control frames to be transferredsimultaneously on both the primary and secondary channels

Back 714

Statement :Non HT duplicate mode

Front 715

Non-HT duplicate transmissions will be sent using 802.11a data rates in the 5 GHz bandor 802.11g data rates in the 2.4 GHz band

Back 715

Statement: Non HT duplicate mode

Front 716

MRC and TxBF will result in greater range. True or False

Back 716

True

Front 717

Chapter 19 essentials

Back 717

1. Difference b/w 11n vs 11ac

2. 20,40,80,160MHZ channels

3. 64QAM and 256QAM

4. MCS in 11ac

5. Explicit beamforming

6. SU-MIMO vs MU-MIMO

7. 11ac data rates

8. Infrastructure requirements for 11ac

9. concerns when deploying 11ac in any environment

Front 718

Maximum theoretical data rate of 802.11 ac

Back 718

6.93Gbps

Front 719

Reason for increased data rate/bandwidth in 802.11 ac

Back 719

1. increased channel bandwidth 80MHz,160MHz

2. more radio chains and spatial streams (upto 8SS)

3. enhanced modulation and coding schemes (upto 256QAM)

Front 720

1st wave of 802.11ac supports data rates upto

Back 720

1.3Gbps

Front 721

802.11 ac operates in 5GHz UNII band

Back 721

Statement: 802.11 ac

Front 722

Back 722

802.11n vs 802.11 ac

Front 723

802.11 ac is backward compatible with PHYs

Back 723

a/n

Front 724

Each subcarrier in a channel is 312.5KHz wide

Back 724

Statement: Subcarrier

Front 725

Total usable subcarriers in 80MHz is slight higher than two 40 MHz channels combined (2x 114 )because some unused subcarriers between the adjacent channels can be used

Back 725

Statement: Subcarrier in 80 MHz

Front 726

160MHz channels are made of two 80 MHz channels. It is not necessary these two 80 MHz channels should be adjacent.

Since two 80 MHz channels are not adjacent unused subcarriers between adjacent channels can't be used

Total subcarriers in 160MHz channels will be 2x subcarriers in 80MHz

Back 726

Statement: Subcarrier in 160 MHz

Front 727

Subcarriers in 80MHz

Back 727

Total 256

Data subcarriers: 234

Pilot: 8

Unused:14

Front 728

Subcarriers in 160MHz

Back 728

Total :512

Data subcarriers: 468

Pilot: 16

Unused:28

Front 729

Number of primary channel in 160 MHz

Back 729

3

one 20MHz primary

one 40 MHz primary

one 80MHz primary

Front 730

160MHz channels are deployed in low density high throughput requirements

Back 730

Statement: 160MHz deployement

Front 731

64QAM can modulates __bits per second

Back 731

2^6 =64

6bits

Front 732

256QAM can modulates __bits per second

Back 732

2^8 = 256

8 bits

Front 733

33 percent of bandwidth increase is achieved by the introduction of 256 QAM modulation. True or False

Back 733

True

Front 734

256 QAM implemented in 2.4GHz is known as

Back 734

Turbo-QAM

Note:

implemented by Broadcom

Front 735

Number of MCS in 802.11ac

Back 735

10

MCS 0-9

Front 736

Mandatory MCS rate for 802.11ac

Back 736

MCS 0-7

Front 737

MCS 8 and 9 are optional. True or False

Back 737

True

Front 738

Unlike previous PHYs 802.11 ac does not allow us to disable individual data rates instead it supports 3 ranges MCS 0-7, MCS 0-8, MCS0-9

Back 738

Statement: MCS rates in 11ac

Front 739

MCS rates which support 256 QAM modulation

Back 739

MCS 8,9

Front 740

code rate representation:

number of user bits

= -------------------------------------

number of bits in channel

Back 740

code rate representation

Front 741

Higher the code rate,higher the data is transmitted and greater chance for corruption

Back 741

Statement: code rate

Front 742

Code rate 5/6 means, out of 6 bits in channel 5 are user bit and 1 is redundant bit. True or False

Back 742

True

Front 743

Maximum number of spatial stream supported in 11ac

Back 743

8

Front 744

Maximum number of spatial stream supported in 11n

Back 744

4

Front 745

Due to technical reasons there are ___ instances certain MCS rates are not applicable

Back 745

10

Front 746

10 instances in which MCS rates are not applicable

Back 746

MCS 6, 80 MHz channel, SS 3,7

MCS 9, 20 MHz channel, SS 1,2,4,5,7,8

MCS 9, 80 MHz channel, SS 6

MCS 9, 160 MHz channel,SS 3

Front 747

MCS 9 is not supported for 20MHz channels

Back 747

Statement: MCS 9

Front 748

Data rate=

20MHz data rate x SS multiplier x channel width multiplier

Back 748

SS multiplier:

x number of SS

Channel width multiplier:

x1.0 for 20MHz

x2.1 for 40 MHz

x4.5 for 80 MHz

x9 for 160 MHz

Eg: AP using MCS3, 4 SS, 80MHz

28.9 x 4 x 4.5 = 520.2 Mbps

Front 749

Total number of available data rates in 11ac

Back 749

310

Note:

(10 x 8 x4) -10 = 310

Total 10 MCS rates

Total 8 SS

Total 4 channel width

Total 10 invalid MCS rates

Front 750

Notification frame send my transmitting station to notify other stations that it is changing the channel width and number of SS it can receive/transmit

Back 750

Operating mode notification frame

Front 751

In 802.11ac all frames are transmitted as A-MPDU even if it is a single frame.

Back 751

Statement: 802.11ac

Front 752

Aggregation shifts some of the frame information from PLCP header to MPDU header.

PLCP information are transmitted at lowest rate and MPDU information are transmitted at highest rate

This improves performance.

Back 752

Statement: Aggregation

Front 753

RIFS is introduced in 802.11n to reduce the time of transmission of multiple frames

In 11ac all frames are sent as aggregated frames at higher data rate followed by block ack.

Aggregation reduces per frame overhead and requirement of RIFS is no longer required

Back 753

Statement: no RIFS in 11ac

Front 754

If an AP wants to transmit using 80 MHz, it will make sure all the four 20MHz channel is available by sending RTS in 11a rates to the client across all the available four channels(non-HT Duplicate mode).

If all the channels are clear or idle, client will be able receive all the RTS and respond back with CTS

When AP receives all the four CTS, it assumes all the 4 channels are available

If AP doesn't receive CTS in any of the channel, it will assume that channel is busy and do the transmission in 40MHz or 20MHz channel in which it received CTS

Back 754

Statement: 11ac channel assessment before transmission

Front 755

Beamforming can occur from AP to client and vice versa. True or False

Back 755

True

Front 756

Beamforming results in 3dB increase in signal

Back 756

Statement: Beamforming

Front 757

Beamforming allows transmitter to focus RF energy to a particular client.

AP sends same information across multiple radio chains by correctly adjusting the phase so that the waves reach the receiver in phase

Back 757

Statement: Beamforming

Front 758

Beamforming can be adjusted frame-by-frame basis. One frame AP can be beamformer and next client can become beamformer

Back 758

Statement: Beamforming

Front 759

Type of beamforming used in 11ac

Back 759

Explicit beamforming

Front 760

Beamformer sends a NDP announcement frame to notifying beamformee its intent to send a beamformed transmission.

AP then sends a NDP frame

Beamformee process each each OFDM subcarrier and creates feedback information.

Feedback information contains regarding power and phase shift between each pair of transmit and receive antennas

This information is used to create feedback and matrix that is then compressed and sent to beamformer

Beamformer use this feedback matrix to create steering matrix that is used to direct data transmission to the beamformee

Back 760

Statement: beamforming process

Front 761

With MU-MIMO 802.11ac APs can can communicate upto ___ clients simultaneously

Back 761

4

Front 762

The goal of MU-MIMO is to use as many spatial streams as possible whether transmission is with one client with 4 SS or with 4 clients with 1SS

Back 762

Statement: MU-MIMO

Front 763

MU-MIMO is supported only in APs due to requirement of advanced signal processing

Back 763

Statement: MU-MIMO

Front 764

AP sends a NDP announcement frame notifying multiple beamformeess to notigy its intend to send a beamformed transmission.

AP then sends a NDP frame

Each beaformee process each OFDM subcarrier and creates feedback information then creates a compressed feedback matrix

First beamformee responds AP with a feedback matrix

AP then polls rest of the beamformees to send the feedback matrix, by sending Beamforming Report Poll frames to them

AP uses these feedback matrix to create a single steering matrix

steering matrix defines transmit parameters between each of the antennas on the AP and each of the antennas on each of the client devices

After MUMIMO transmission, AP sends BAR to each clients sequentially and collects BlockAck to verify frame delivery

Back 764

Statement: MU-MIMO process

Front 765

If beamformees are close together they may experience inter-user interference. They will receive signals beamed towards other clients

Back 765

Statement: MU-MIMO

Front 766

The AP will initiate a transmission from whichever access category is next in line. This is known as the primary access category, and all others are known as secondaryaccess categories.

The AP can transmit additional frames (one or more) from primary or secondary access categories, providing that the frames are shorter thanthe primary frame.

AP transmit using a multi user frame

During transmission of each multiuser frame, low priority frames are added along with high priority frames as long as they don't increase the transmission time of primary data and clients they are being sent are spatially distinct

AP verifies the successful transmission with Block ACK

Back 766

Statement: MU-MIMO Access category

Front 767

Mandatory features tested Wifi alliance 11ac certification

Back 767

WMM

WPA2

20,40,80MHz

MCS 0-7

one SS for clients and 2 SS for APs

Long guard interval 800ns

Front 768

VHT radios use modulation and coding schemes to define data rates based on

Back 768

Modulation and code rate

Front 769

Back 769

Statement: Subcarriers legacy/HT/VHT

Front 770

Power required for 802.11 ac APs

Back 770

PoE+

Front 771

Normal enterprise APs are powered by 802.3 af compliant PoE

Back 771

Statement: power supply to APs

Front 772

Back 772

FHSS

Front 773

Back 773

Installation of lightning protectors

Front 774

Back 774

Indoor sectorized array

Eg for static beamforming

Front 775

Back 775

Beamwidth calculated at half power points

Front 776

Back 776

Fresnel zone

Front 777

Chapter 12 essentials

Back 777

1. Causes of layer 2 retransmissions: multipath, hidden nodes, mismatched power settings,RF interference, low SNR, near/far problems, and adjacent channel interference. Layer 2retransmissions affect throughput, latency, and jitter

2. Dynamic rate switching

3. Various aspects of roaming

4. adjacent channel vs co-channel interference

5. MCA vs SCA wireless design

6. various types of interference

7. hidden node problem

8. importance of channel reuse

9. aspects of band steering, load balancing and high density wlans

10. consequences of weather conditions

Front 778

Tool used by WLAN engineers to troubleshoot layer 1 issues

Back 778

Spectrum analyzer

Front 779

Tool used by WLAN engineers to troubleshoot layer 2 issues

Back 779

Protocol analyzer

Front 780

Possible results of excessive layer 2 transmission

Back 780

1. decrease in throughput

2. latency and jitter to time sensitive applications like voice and video

Front 781

Latency Vs Jitter

Back 781

Latency is time taken to deliver the packet from source to destination

Jitter is variation in latency. Sometimes packet delivery takes less time sometimes more time.

Jitter measures latency of each packet on an average.

Front 782

If all packets are delivered at same time in network, value of jitter will be __

Back 782

zero

Front 783

Jitter will result in

Back 783

1. choppy audio transmission

2. battery drainage of voip phones due to increased layer 2 transmission

Front 784

Data applications in WiFi network can handle layer 2 transmissions upto __ percent without any noticeable performance degredance

Back 784

10

Front 785

VoWifi networks has to limit layer 2 transmission upto __ percent to ensure timely and consistent delivery of voip packets

Back 785

Statement:vowifi networks layer 2 transmission

Front 786

time sensitive applications like voip requires higher lay IP packet loss be no greater than 2 percent

Back 786

statement: voip ip packet

Front 787

How can we measure layer 2 retransmissons

Back 787

layer 2 retry statistics thru a protocol analyzer

WLAN controller

NMS server

Front 788

Layer 2 retransmissions are mainly used caused by

Back 788

layer 1 issues: RF interference

result of an improper wlan design

Front 789

Different types of RF interferences that causes layer 2 retransmissions

Back 789

1. Narrow band interference

2. Wide band interference

3. all band interference

Front 790

Narrow band signals are very high amplitude signals which occupies smaller and finite frequency space

can completely disrupt 802.11 communications in the frequency it is transmitting

will not cause denial of service of entire band like complete 2.4GHz ISM band but few channels can be affected

Back 790

Statement: Narrow band signals

Front 791

If the transmitting signal has a capability to disrupt communication in entire band it is considered as wide band interference

can cause denial of service in entire band

Back 791

Statement: wide band interference

Front 792

All band interference are caused by devices using FHSS

device like bluetooth, medical telemetry units, Home RF are sources of all band interference

while hopping and dwelling FHSS devices will transmit sections of frequency where 802.11 devices are transmitting

Back 792

Statement: all band interference

Front 793

Narrow band,Wide band and all band interference sources can be located and removed using __

Back 793

spectrum analyzer

Front 794

Majority of RF interference occur in 2.4GHz band

Back 794

Statement: RF interference

Front 795

Layer 2 retransmission caused by multipath are affected only to older a/b/g radios

Multipath cause intersymbol interference(ISI)

antenna diversity, using semi directional antennas are few workarounds to survive multipath when a/b/g radios are used

radios using MIMO are not affected due to multipath instead they make use of multipath to achieve greater wlan performance

Back 795

Statement: multipath

Front 796

If there is no RF interference is found in RF site survey and there is layer 2 retransmission possible cause can be __

Back 796

multipath

Front 797

multipath in indoor cannot be avoided because some reflections will always occur. True or False

Back 797

True

Front 798

WLAN vendor which provides wlan troubleshooting tools that can detect and visualize occurance of multipath and delay spread into a useful graphical display

Back 798

Berkeley Varitronics Systems

Front 799

Indoor MIMO patch antennas are used in high density environments like gymnasium

Back 799

Statement: usecase of MIMO patch antennas

Front 800

a channel is considered adjacent channel if it is immediately above or below the current numbered channel

eg: for channel 3 , 4 and 2 are adjacent channels

Back 800

Statement: adjacent channel

Front 801

while designing wlan, for seamless roaming overlapping coverage cells are required

These overlapping cells should not have overlapping frequencies

In 2.4GHz we have only 3 non overlapping channels

overlapping coverage cells with overlapping frequencies will cause adjacent channel interference

adjacent channel interference will corrupt the frames and causes layer 2 retransmission

Back 801

adjacent channel interference

Front 802

In 5GHz all the 25 channels are non overlapping channels because

Back 802

20 MHz of separation between the center frequencies

Front 803

Signal to noise ratio is not a ratio

It is the difference in decibels between received signal and noise floor

Back 803

SNR

Front 804

A wlan with SNR 25 dB or above is considered good signal quality

Back 804

Statement:SNR

Front 805

A wlan with SNR 10 dB or below is considered good signal quality

Back 805

Statement:SNR

Front 806

A low SNR will casue layer 2 retransmissions

Back 806

Statement:SNR

Front 807

When designing coverage during site survey, the normal recommended best practiceis to provide for a –70 dBm or stronger received signal that is well above the noise floor.

Back 807

Statement:SNR

Front 808

When designing for WLANs with VoWiFi clients, a –67 dBm or stronger signal that is evenhigher above the noise is recommended.

Back 808

Statement:SNR

Front 809

Recommended SNR for wifi data network

Back 809

20dB

Front 810

Recommended SNR for vowifi network

Back 810

25dB

Front 811

Wlan troubleshooting tool used to measure SNR

Back 811

spectrum analyzer

Front 812

Mismatched power setting:

Tx power of AP should match lowest powered client station.

majority of clients are mobile devices with lowest txpower. If Ap increase txpower it might increase range but the transmission from client cannot reach AP due to its low tx power.

To increase range, instead of increasing tx power use a high gain antenna. Antenna will amplify outgoing signal and received signal

Back 812

Mismatched power setting

Front 813

Use a protocol analyzer to identify layer 2 retransmission are caused due to mismatched power setting

An AP/client power problem exists if the frame transmissions of the clientstation are corrupted when you listen near the access point but are not corrupted whenyou listen near the client station

Back 813

Mismatched power setting troubleshooting

Front 814

Near/Far problem:

occurs due to tx power mismatch b/w multiple clients in same BSS

if there a client with high tx power near Ap, it will increase the noise floor of AP . So transmission from client far from Ap with low tx power will be unheard.

The problem is often caused by AP's inability to distinguish high amplitude signal and low amplitude signal subsequently

can troubleshoot using the same way we troubleshooted mismatched txpower settings

Back 814

Near/Far problem

Front 815

How to negate near/far issues:

CSMA/CA usually averts the near/far problem.

well plannedWLAN that provides for –70 dBm or stronger coverage

Back 815

Near/Far problem

Front 816

Hidden node problem:

2 clients of a rf coverage cell cannot hear each other and both trying to send at same time

Back 816

hidden node

Front 817

Overcome hidden node by

Back 817

RTS/CTS in hidden node

remove obstacles

increase power of all stations

move hidden station if possible

add another AP

Front 818

Layer 2 retransmission reasons

Back 818

RF interference: Narrow band,wide band, all band

Multipath

Adjacent channel interference

Low SNR

Mismatched power setting

Near/Far problem

Hidden node

Front 819

When client move away from the AP, it will downshift to less complex modulation with low data rates and when it move closer it up shifts to higher data rates to improve wlan performance. This mechanism is known as

Back 819

Dynamic rate switching

Front 820

DRS is also known as

Back 820

Dynamic rate shifting

Adaptive rate selection

Automatic rate selection

Front 821

Back 821

DRS

Front 822

Threshold used for DRS are vendor proprietary

It can be based on RSSI, packet error rates, retransmissions

Back 822

DRS

Front 823

Why lower data rates of AP are disabled by WLAN admins

Back 823

1. to decrease coverage area

2. to avoid hidden node issue

3. sticky roaming client

4. to avoid medium contention overhead caused by clients using low data rates. If airtime fairness is introduced no need to disable lower data rates

Front 824

Roaming is transition of client from one AP to another AP within the saem ESS without losing upper layer connectivity.

Roaming decision is made by client and its proprietary

For seamless roaming there should be 15-30 percent coverage overlap of -70dBm cells

Back 824

Roaming

Front 825

802.1x takes an average of __ milliseconds for authentication during roaming

Back 825

700

Front 826

VoWifi networks requires a roaming handoff of__miliseconds

Back 826

150

Front 827

Non standard method of fast secure roaming implemented by most vendors

Back 827

OKC

Front 828

IEEE standard for fast secure roaming

Back 828

FT

Front 829

For troubleshooting roaming issues wlan engineers require protocol analyzers which support multi channel monitoring capabilities with multiple wlan cards with monitoring capabilities each on different channel 1,6,11.

Back 829

Front 830

IEEE standards which enhance roaming perfomance

Back 830

802.11k, 802.11 r

Front 831

Roaming is a layer 2 process

while roaming, client has to maintain layer 3 connectivity.

When it roams from one AP to another in different subnet, client must acquire new IP address which means it has to reestablish layer3 connectivity

IETF introduced Mobile IP solution which allows client to maintain original IP address when it roams from one layer 3 network to another

Back 831

Layer 3 roaming

Front 832

Mobile IP is defined in RFC 3344

Back 832

Statement: Mobile IP

Front 833

IP address of roaming client is Home address

Controller to which client originally connected is known as Home Agent(HA)

Controller present in network to which client roams is known as Foreign Agent(FA)

HA shares Home Address Table with FA, which contains client's MAC/IP information

When client roams to a network in FA resides, FA uses HAT to locate HA of the roaming client

FA contacts HA and setup a Mobile IP tunnel to FA

FA then delivers all the traffic to the client thru this tunnel and client can maintain its original IP address

WLAN architecture in which there is no controller, tunnelling occurs between APs that assumes role of HA and FA

Back 833

Front 834

The unnecessary medium contention overhead that occursbecause all the APs are on the same channel is called __

Back 834

co-channel interference (CCI).

Front 835

Reason for co-channel interference

Back 835

when overlapping coverage cells are on the same channel

Front 836

Back 836

co-channel interfernce

Front 837

Back 837

Adjacent channel interference

occurs when overlapping coverage cells have overlapping channels resulting in data corruption and layer 2 retransmission

Front 838

Back 838

2.4GHz channel reuse multi channel architecture

Front 839

Back 839

5GHz channel reuse multi channel architecture

Front 840

In 5GHz channel 120,124,128 are not used for channel reuse because they are used TDWR and FCC defines (DFS) regulations that restrict use of the5600 MHz–5650 MHz frequency band

Back 840

Statement: 5GHz channel reuse

Front 841

Back 841

Three-dimensional channel reuse

When APs are mounted on multiple floor, make sure their channels don't overlap as shown in fig

5 GHz, and the signal will attenuate faster than the signalthat is being transmitted at 2.4 GHz from the 802.11b/g/n radio

when performinga site survey for deploying dual-frequency WLANs, you should perform the 5 GHzsite survey first and determine the placement of the access points.

After those locations areidentified, channel reuse patterns will have to be used for each respective frequency

Front 842

Back 842

Channel reuse/Channel bonding

1. 2.4GHz 40MHz is not used

2. In 5Ghz we have 25 , 20MHz channels, when channel bonded =12 40MHz channels

3. Channels in DFS range are not used , so channels in UNII 1 and UNII 3 are only used

36,40,44,48 and 149,153, 157, 161

Front 843

Back 843

Current UNII channels

Front 844

Back 844

All the APs will be connected to a single wlan controller

Each APs will have its own radio and its own mac address but all will have same virtual BSSID that is broadcast from all APs

the multiple access points advertise only one single virtual MAC address(BSSID), client stations believe they are connected to only a single access point, althoughthey may be roaming across multiple physical APs

the clients think theyare associated to only one AP, so they never initiate a layer 2 roaming exchange. All of theroaming handoffs are handled by a central WLAN controller

Front 845

Main advantage of virtual AP SCA

Back 845

zero handoff time while roaming

no adjacent channel interference

Front 846

Disadvantage of SCA

Back 846

co-location of multiple APs for capacity a.k.a channel stacking

multiple APs maybe co-located by using 3 channels and 3 BSSIDs

each layer of multiple APs on a single channel and using same virtual BSSID is known as channel blanket or channel span

Front 847

802.11 coverage consideration

Back 847

1. Dynamic rate switching DRS

2. Roaming

3. Layer 3 roaming

4. Co-channel interference

5. Channel reuse/ multi-channel architecture MCA

6. Channel reuse/ channel bonding

7. Single channel architecture SCA

Front 848

Capacity Vs Coverage

Back 848

client stations connected to access point share the throughput capabilities of that access point

as a wlan engineer it is important to design and decide number of client stations that can connect to a single AP simultaneously

In MCA environment , determine the cell size

and limit the coverage cell size by adjusting tx power to get desired cell size

Adjusting the transmit power to limit the coverage area is known as cell sizingand is the most common method of meeting capacity needs in an MCA environment

Front 849

Band Steering

Back 849

a technology to encourage dual band client radios to connect to 5GHz AP radio instead of 2.4GHz AP radio

Client sends probe request in both 2.4 and 5GHz band

When AP sees probe request in both 2.4 and 5 GHZ from same MAC address it responds back with probe response only in 5GHZ

So client connects with 5GHz AP radio

Band steering is used in environment where high density of clientdevices exists, band steering to both frequencies can be used to balance an almost equalnumber of clients to both of the radios in the AP.

Front 850

When client wants to connect to an AP it sends an assoc req to that AP

If that AP has already overloaded with clients it will defer from sending assoc response assuming client will send another assoc req to neighboring AP with less client connected

load balancing information is shared among all the APs

Back 850

Load balancing

Front 851

Load balancing is __plane mechanism

Back 851

control

Front 852

Load balancing works for centralized wlan architecture as well as distributed wlan architecture. True or False

Back 852

True

Front 853

Load balancing is implemented in high density client environments where roaming is not a priority. True or False

Back 853

True

Front 854

Load balancing is detrimental to roaming process. True or False

Back 854

True

Front 855

General rules for high density wlans

Back 855

1. deploy 11n or 11ac APs as opposed to legacy

2. disable 11b rates

3. deploy only 11n or 11ac clients and select high minimum data rates such as 18MBps

4. lower AP tx power for cell sizing and avoid co-channel interference

5. For stability use static channel and power settings instead of dynamic RF

6. enable load mechanism b/w multiple APs

7. In 5GHz if DFS channels are supported cut down to 20MHz. if client devices support DFS and channel bonding go for 40MHz

8. consider using sectorized MIMO patch antennas to provide sectorized coverage

9. disable few 2.4 GHz radios to avoid co-channel interference

Front 856

Number of devices per AP radio =

B.W used by application

80 ÷ ------------------------------------------------------------

Throughput of single device using that app

Back 856

Statement: Number of devices per AP radio

Note:

airtime consumption =

B.W used by application

------------------------------------------------------------ Throughput of single device using that app

Front 857

An 802.11 access point is considered to be fully burdened at about 80 percentof airtime utilization

Back 857

Statement: airtime consumption

Front 858

Possible side effects of over sized coverage cells

Back 858

1. CCI

2. hidden node

3. AP may not hear transmission of client with low tx power

Front 859

recommended power setting for higher density environment

Back 859

1mW

Front 860

Increasing of tx power is not a recommended option to increase coverage .

To increase coverage use a high gain antenna

Back 860

Statement: coverage

Front 861

WLAN performance considerations

Back 861

1. Tx power rates

2. Antenna gain

3. Antenna type

4. Wavelength

5. Free space path loss

6. physical environment

7. CSMA/CA

8. ENcryption overhead

9. Application used

10. Number of clients

11. Layer 2 transmissions

Front 862

Consequences of weather conditions in wlan

Back 862

1. Lightning

2. Wind

3. Water

4. Air stratification

5. UV/Sun

Front 863

Chapter 13 essentials

Back 863

1. AAA concepts

2. legacy 802.11 security

3. EAP framework

4. requirements for RSN n/w

5. TKIP/RC4, AES/CCMP

6. VLANS and VPNs

7. Guest WLAN security

Front 864

802.11 security basics

Back 864

1. Data privacy and integrity

2. Authentication, Authorization, Accounting

3. Segmentation

4. Monitoring and policy

Front 865

Data privacy and integrity

Back 865

privacy is achieved by encrypting upper layer data (MSDUs) using encryption algorithms like RC4, AES

RC4 is streaming cipher used in WEP and TKIP

AES is block cipher used in CCMP

Integrity is achieved by:

ICV in WEP

MIC in TKIP, CCMP

MIC in CCMP is stronger than MIC in TKIP

ICV in WEP is considered as weaker

Front 866

Authentication, Authorization, Accounting

Back 866

Authentication: Whether user have right credentials to join the n/w

Authorization: privileges given to authenticated user to access n/w resources based on group,device,time of the day, locations

Accounting: keeping track of access details of n/w resource by authenticated user

Front 867

Segmentation

Back 867

Separating user traffic in a network based on device type, roles

Achieved using VLANs, firewall, routers, VPNs

Front 868

Monitoring and Policy

Back 868

Monitoring WLAN networks for n/w attacks

Achieved using WIDS

Front 869

Legacy Security

Back 869

provide 2 types of authentication: Open, Shared

used in WEP

Front 870

WEP

Back 870

Wired Equivalent Privacy

uses RC4 algorithm for encryption and ICV for integrity check

WEP supports 64 bit and 128 bit

WEP supports 4 static keys either in 64bit or 128 bit . Uses any one of it for data encryption

Front 871

64 bit WEP key contains

Back 871

24 bit IV and 40 bit static key

Front 872

128 bit WEP key contains

Back 872

24 bit IV and 128 bit static key

Front 873

40 bit static key can be ascii or hex. How many characters will it have

Back 873

ascii: 5 characters

hex: 10 characters

Front 874

128 bit static key can be ascii or hex. How many characters will it have

Back 874

ascii: 13 characters

hex: 26 characters

Front 875

Back 875

Static WEP key

Front 876

Back 876

WEP encryption

Front 877

WEP weakness

Back 877

IV collision attack: 24bit IV is driver generated It is limited and will be reused. IV is send as cleartect with encrypted frame

Weak key attack: coz weak RC4 scheduling algorithm weak IVs are generated and with theses IV secret keys can be recovered

Reinjection attack: used in n/w with less traffic packets are injected to recover weak IVs

Bit flipping attack: tampering wep encrypted frames

Front 878

MAC filtering

Back 878

Using MAC address to allow or deny access to network

MAC address can be easily spoofed and mac filtering is considered weak

Front 879

SSID cloaking

Back 879

making ssid hidden

can make connection by sending directed probe req

SSID cloaking is considered weak coz anyone with a protocol analyzer can capture these packets and can start attacks

Front 880

Robust security network

Back 880

A robust security network is one which allows only rsn associations

2 STAs should authenticate each other and create dynamic encryption keys using 4 way handshake

RSN capability is present in RSN IE in beacons,prob req/res, (re)assoc req/res

WPA/TKIP, WPA enterprise WPA2/AES, WPA2 enterprise creates dynamic encryption keys

Front 881

PSK is ideal for ___ environment

Back 881

SOHO

Front 882

802.1x is ideal for __environment

Back 882

enterprise

Front 883

802.1x is ideal for enterprise environment because it requires RADIUS server and advanced skills are required to support it

Back 883

Statement: 802.1x

Front 884

Passphrase size used in wpa2-psk

Back 884

8 to 63

Front 885

WPA personal vs WPA2 personal

Back 885

both uses PSK

WPA uses TKIP/RC4

WP2 uses AES/CCMP

Front 886

Wi-Fi Alliance name for PSK authentication is

Back 886

WPA-Personal or WPA2-Personal.

Front 887

Wlan vendors which provides uniques psk for each client dynamically

Back 887

Aerohive Networks’ Private PSK and Ruckus WirelessDynamic PSK

Front 888

A database of unique PSKs mapped to usernames or client stations must be stored on allaccess points or on a centralized WLAN controller.

Individual users are then assigned aunique PSK that is created either dynamically or manually theauthenticator maintains a database of each individual PSK for each individual client.

ThePSKs that are generated can also have an expiration date. Unique time-based PSKs can alsobe used in a guest WLAN environment as a replacement for more traditional username/password credentials

Back 888

Dynamic psk generation

Front 889

Advantages os proprietary psk solution

Back 889

no need of complex configuration like 802.1x

Front 890

Back 890

Proprietary PSK

Front 891

802.1X/EAP Framework

Back 891

3 components

1. Supplicant: client who want to access n/w resources

2. Authenticator: usually an AP. Maintains two virtual port blocked and unblocked

will not allow any n/w traffic to pass thru blocked port until client credential are verified

unblocked port allows only EAP packets for authentication purpose

3. Authentication server: usually a RADIUS server. verifies credentials of supplicant and if verified inform AP to open blocked port to allow client to access n/w resources

Front 892

RADIUS is

Back 892

Remote Dial in User service

Front 893

802.1X security solution is used with a WLAN controller solution, theWLAN controller is typically the authenticator and not the controller-based access points

Back 893

Statement: 802.1x Authenticator

Front 894

Back 894

802.1X comparison—standalone vs. controller-based access points

Front 895

Back 895

the root bridge would be the authenticator and the nonrootbridge would be the supplicant if 802.1X security is used in a WLAN bridged network

Front 896

Back 896

802.1X/EAP authentication

Front 897

4 way handshake

Back 897

method for creating dynamic encryption keys PTK and GTK

PTK for unicast and GTK for group traffic

The 4-Way Handshake will always be the final four frames exchangedduring either an 802.1X/EAP authentication or a PSK authentication

Front 898

TKIP rectify the problems that were inherent in WEP which are

Back 898

TKIP starts with a 128-bit temporal key that is combined with a 48-bit initializationvector (IV) and source and destination MAC addresses in a complicated process known asper-packet key mixing. (TK+PN+SMAC+DMAC)

This key-mixing process mitigates the known IV collision and weakkey attacks used against WEP.

TKIP also uses a sequencing method to mitigate the reinjectionattacks used against WEP.

TKIP uses a stronger data integrity checkknown as the message integrity check (MIC) to mitigate known bit-flipping attacks againstWEP.

The MIC is sometimes referred to by the nickname Michael.

All TKIP encryptionkeys are dynamically generated as a final result of the 4-Way Handshake.

Front 899

11n and 11ac doesn't permit use of TKIP or WEP. True or False

Back 899

True

Front 900

CCMP is

Back 900

CTR with CBC MAC

Counter mode with cipher block chaining message authentication code protocol

Front 901

CCMP/AES uses a 128-bit encryption-key size and encrypts in 128-bit fixed-length blocks.

Back 901

CCMP

Front 902

CCMP uses __alogorithm

Back 902

AES(Rijndael algorithm)

Front 903

By upgrading the firmware older wlan devices can support CCMP. True or False

Back 903

False

AES cipher is processor intensive, older legacy 802.11 devices donot have the processing power necessary to perform AES calculations

Front 904

Traffic segmentation is achieved by

Back 904

VLAN

RBAC

Front 905

VLAN

Back 905

create separate broadcast domains in alayer 2 network and are often used to restrict access to network resources without regardto physical topology of the network

Guest VLAN, Voice VLAN, Enterprise VLAN are the VLANS usually created by enterprise

In enterprise environment, VLAN assignment done with the help of Attribute value pairs present in Radius_accept packet

Front 906

RBAC

Back 906

Role Based access control

approach is users, roles , permissions,

once user is authenticated depending on their roles they have given permission to access n/w resources

Permissions can be defined as layer 2permissions (VLANS or MAC filters), layer 3 permissions (access control lists), layers 4–7permissions (stateful firewall rules), and bandwidth permissions

Front 907

Infrastructure security

Back 907

1. physical security

2. interface security

Front 908

physical security

Back 908

enterprise wlan products are expensive and has to prevent it from theft by locking them in enclosures

it also prevents unwanted users from gaining access to AP using serial cables or console cables

Front 909

interface security

Back 909

telnet should be disabled

use only ssh

change default passwords

disable interface which are not using CLI or Web based

configure wireless devices from wired side

Front 910

It is recommended practice to configure infrastructure device from wired side. Reason behind this

Back 910

If devices are configuredfrom the wireless side, an intruder might be able to capture your wireless packets and beable to watch what you are doing

When performing administration through a wireless connection, there is also a chance thatyou will accidentally lock yourself out of the device while configuring Wi-Fi hardware thatyou are connecting through.

Front 911

VPN

Back 911

Virtual private network

provides layer 3 security

2 types : router-to-router, client server based

VPN create a secure tunnel between two networks encapsulates original IP packets and securely send to destination

Commonly used VPN is IPsec which supports ciphers 3DES, DES, AES

IPSec requires client to be installed on remote machine that connects to VPN server

IPsec VPNS are NAT-transversal

any firewalls at a remote site require (at a minimum) that UDP ports 4500 and 500 beopen. A

Front 912

SSL VPN

Back 912

no need to install client software

user connects to ssl vpn server using web browser

traffic b/w browser and vpn server are encrypted using SSL or TLS

uses asymmetric cryptography for privacy and a keyed message authentication code formessage reliability.

Front 913

SSL VPn is chosen over IPSec because

Back 913

NAT issues, firewall policy at remote locations

Front 914

common use of VPN technology is to provide site-to-site connectivity betweena remote office and a corporate office.

Back 914

VPN

Front 915

Back 915

VPN Deployment

Front 916

Back 916

Site-to-site VPN

Front 917

Guest WLAN

Back 917

to provide internet access to visitors,

contractors,sales people

Front 918

Guest WLAN security

Back 918

to provide internet access to visitors with less hurdles and sametime prevent them from accessing corporate n/w

security components :

Guest VLAN, Guest SSID, Firewall policy, Captive portal, Guest management solution

Front 919

A captive portal is essentiallythe integration of a firewall with an authentication web page.

Back 919

captive portal

Front 920

Chapter 14 essentials

Back 920

1. Different types of wireless attacks

2. Intrusion monitoring

3. Wireless security policy

Front 921

components that should be mandatory in every remote access wireless securitypolicy

Back 921

Encrypted VPN

Personal firewall

Front 922

attacks which wireless users susceptible to at a public-access hotspot

Back 922

1. Wi-Fi phishing

2. Peer-to-peer attack

3. Malicious eavesdropping

4. Man-in-middle

5. Wireless hijacking

Front 923

actions should be taken after the WIPS detects the rogue AP

Back 923

1. Enable the layer 2 rogue containment feature that his WIPS provides.

2. Unplug the rogue AP from the data port upon discovery.

Front 924

two solutions that can help mitigate peer-to-peer attacks from other clients associatedto the same 802.11 access point

Back 924

Personal firewall

Client isolation

Front 925

unintentional RF jamming attacks against an 802.11 wireless network

Back 925

1. Microwave oven

2. 2.4 GHz cordless phones

Front 926

when attacker compromises psk he can decrypt the packets and access n/w resources

Back 926

Statement: PSK compromised

Front 927

The only way to prevent a wireless hijacking, man-in-the-middle, and/orWi-Fi phishing attack is to use a __

Back 927

mutual authentication solution

Note:

802.1X/EAP authenticationsolutions require that mutual authentication credentials be exchanged before auser can be authorized

Front 928

Examples for malicious eavesdropping

Back 928

Packet reconstruction

Protocol analyzer capture

Front 929

Different types of wireless attacks

Back 929

1. Rogue wireless devices

2. peer-to-peer attacks

3. Eavesdropping

4. Encryption cracking

5. Authentication attacks

6. Mac spoofing

7. Management interface exploits

8. Wireless hijacking

9. Denial of service(Dos)

10. Vendor-specific attacks

11. Social engineering

Front 930

Intrusion monitoring

Back 930

1. WIDS

2. WIPS

3. Mobile WIDS

4. Spectrum analyzer

Front 931

A rogue accesspoint is any unauthorized Wi-Fi device that is not under the management of the propernetwork administrators.

Back 931

Statement: Rogue AP

Front 932

2 types of eaves dropping

Back 932

Casual eavesdropping

Malicious eavesdropping

Front 933

Offline dictionary attack is an example for __

Back 933

Authentication attack

Front 934

How can we prevent authentication attacks

Back 934

802.1X solution which provide mutual authentication and dynamic keys

proprietary PSK solutions which provides unique PSK to each client

Front 935

How to avoid management interface exploits

Back 935

use only SSH or HTTPS enabled encrypted login

strong passwords should be used

disable unused management interfaces

change default passwords

use wired network while configuring infrastructure device

Front 936

Wireless Hijacking is also known as

Back 936

evil twin attack

Front 937

2 types of RF jamming

Back 937

Intentional jamming

Unintentional jamming

Front 938

Jamming caused by microwave ovens, cordlessphones is ___ jamming

Back 938

unintentional

Front 939

Jamming casued by signal generator to cause interference in unlicensed frequency space is a an example for ___ jamming

Back 939

intentional

Front 940

Tool used to detect RF jamming

Back 940

spectrum analyzer

Front 941

DoS

Back 941

RF jamming

Deauthentication and Dissociation by spoofing MAC address

Association floods

Authentication floods

PS-POLL floods

virtual carrier attacks

Front 942

Tools to detect DoS attack

Back 942

Spectrum analyzer

Protocol analyzer or WIDS

Physical security

Front 943

802.11 w protects from DoS attacks by spoofing management frames like disassoc,deauth, action frames

Back 943

Statement:Management frame protection

Front 944

WIDS components

Back 944

typical WIDS is client server model consists of 3 components

1. WIDS server:

can be s/w or h/w server

server uses signature analysis, behavioural analysis, protocol analysis, RF spectrum analysis, performance analysis to detect potential threats

2. Management consoles: portal to connect to wids server

3. Sensors: are 802.11 radios in monitoring mode

Front 945

Back 945

WIDS

Front 946

3 different types of WIDS

Back 946

1. Overlay:

Expensive and more features

Dedicated WIDS server and sensors which are not part of WLAN solution that provides access to clients

2. Integrated:

less expensive

less features as compared to overlay model

comes along with wlan controller, NMS or AP

3. Integration Enabled:

integrate APs with WIDS vendors

APs are turned into sensors and communicate info to third party WIDS server

Front 947

Overlay WIDS are mostly used in defense, finance, retail vertical markets

Back 947

Statement: Overlay WIDS

Front 948

Most commonly used WIDS model

Back 948

Integrated WIDS

Front 949

WIDS vs WIPS

Back 949

WIDS: detects potential threats

WIPS: detects and mitigate the threats

Front 950

WIPS classifies client radios into 4

Back 950

1. Infrastructure device:

any client station or AP that is an authorizedmember of the company’s wireless network

2. Unknown device:

any new802.11 radios that have been detected but not classified as a rogue or infrastructure device

3. Known device:

device whose identity is known

4. Rogue device:

device which is a potential threat

Front 951

WIPS also use a wired-side termination process to effectively mitigate roguedevices

The wired-side termination method of rogue mitigation uses the Simple NetworkManagement Protocol (SNMP) for port suppression.

Many WIPSs can determine that the rogue AP is connected to the wired infrastructure and may be able to use SNMP to disablethe managed switch port that is connected to the rogue AP.

If the switch port is closed, theattacker cannot access network resources that are behind the rogue AP.

Back 951

Statement: WIPS action on Rogue devices

Front 952

Mobile WIDS

Back 952

essentially a protocol analyzer with layer 1 decoding capabilities

uses 802.11 radios as sensors

advantage: Mobility

The mobile WIDS locks ontothe RF signal of the rogue device, and then an administrator can locate the transmittingrogue by using a directional antenna

Front 953

A spectrum analyzer is a ___ domain tool that can detect any RF signal in the frequencyrange that is being scanned.

Back 953

frequency

Front 954

Two major areas that should be addressed while designing a wireless policy document

Back 954

1. General policy

2. Functional policy

Front 955

General Policy

Back 955

depicts why wireless policy is required for the organization

It defines:

Statement of Authority: The statement of authority defines who put the wireless policy inplace and the executive management that backs the policy.

Applicable Audience: The applicable audience is the audience to whom the policy applies,such as employees, visitors, and contractors.

Violation Reporting Procedures: Violation reporting procedures define how the wirelesssecurity policy will be enforced, including what actions should be taken and who is incharge of enforcement.

Risk Assessment and Threat Analysis: The risk assessment and threat analysis defines thepotential wireless security risks and threats and what the financial impact will be on thecompany if a successful attack occurs.

Security Auditing: Internal auditing procedures, as well as the need for independent outsideaudits, should also be defined

Front 956

Functional Security Policy

Back 956

Defines technical aspects of wireless security

tells how to secure wireless network in terms of what solution and actions needed

It defines:

Policy Essentials: Basic security procedures, such as password policies, training, andproper usage of the wireless network, are policy essentials and should be defined.

Baseline Practices: Baseline practices define minimum wireless security practices such asconfiguration checklists, staging and testing procedures, and so on.

Design and Implementation:The actual authentication, encryption, and segmentationsolutions that are to be put in place are defined.

Monitoring and Response: All wireless intrusion detection procedures and the appropriateresponse to alarms are defined.

Front 957

Legislative Compliance

Back 957

NIST: FIPS 140-2

HIPAA:The Health Insurance Portability and Accountability Act

The goal is to protect patient information andmaintain privacy

Sarbanes-Oxley: The Sarbanes-Oxley Act of 2002

GLBA:The Gramm-Leach-Bliley Act

goal is to protect personal information such as credit card numbers, Social Security numbers from

Front 958

PCI compliance

Back 958

Payment card industry data security standard

regulations for organizations processing and storing cardholder information

Front 959

802.11 policy recommendation

Back 959

1. BYOD policy

2. Remote-Access wlan policy

3. Rogue AP policy

4. Ad Hoc Policy

5. WLAN proper use policy

6. IDS policy

Front 960

Chapter 15 essentials

Back 960

1. WLAN site survey interview

2. Documentation and forms:

identify all the documents required before and after the site survey

3. Vertical market considerations:

requirements will change depending on verticals we choose like healthcare,retails etc.

Front 961

Why site survey is required?

Back 961

to educate the customer and properly determine their requirement

Front 962

Wlan site survey interview

Back 962

1. Customer briefing

2. Business requirements

3. Capacity and coverage requirements

4. Existing wireless network

5. Infrastructure connectivity

6. Security expectations

7. Guest access

Front 963

Customer briefing

Back 963

Brief him on advantages of choosing wifi over wired(about mobility)

Educate customer why a RF site survey is required

Brief him on:

difference b/w throughput vs bandwidth.

Throughput will be always 50 percent less than advertised data rate

RF propagation behavior. How RF waves propagate and attenuate and how site survey helps to ensure proper coverage,capacity and performance of wlan

difference b/w 2.4 and 5GHz

Front 964

Business requirements

Back 964

1. What is the purpose of WLAN

is it for internet gateway, infrastructure connectivity

2. What applications will be used

data or voice or bandwidth intensive or less bandwidth intensive

3. Who will be using WLAN

what kinda users will be using wlan

4. What types of devices will be connecting to WLAN

personal devices,infrastructure devices, barcode scanners, BYOD, MDM solutions needed?

Front 965

Capacity and coverage requirements

Back 965

Coverage:

Get the floor plan and enquire about locations in which coverage is required. Barcode scanner doesn't need coverage till front office other than warehouse, laptops doesn't need coverage in courtyard or storage area etc

Capacity:

1. Data applications used

what kinda data application will be used and how many user will be using it

How many simultaneous client will be connected to single AP radio

2. Users and device density

how many users need wireless access and how many devices they will be using

how many users and devices need wireless access in future

Where are the users located. Is it 1 or 2 members in a room or 30 members in a common area separated by cubicle

plan to conduct site survey during office hours and non office hours

3: Peak hours of usage

4: Existing wireless transmitters like microwave,BT mouse

5: Portability/Mobility

6: Backward compatibility with legacy devices

Front 966

Existing wireless network

Back 966

5 factors:

1: What is the issue with existing WLAN n/w?

2: Are there any known source of interference?

3: Is there any coverage dead zones?

4: Does previous site survey data exists?

5: What equipment is currently installed?

Front 967

Infrastructure connectivity

Back 967

10 factors

1: Roaming

2: Wiring closet->100 feet

3: Antenna structure-> for roof/outdoor

4: Switches->managed/unmanaged

5: PoE-> CAT5e

6: Segmentation of WLAN from wired n/w

7: Naming convention

8: User management->RADIUS,RBAC

9: Device management->BYOD,MDM

10: Infrastructure management->NMS

Front 968

A comprehensive site interview that provides detailed feedback about infrastructureconnectivity requirements will result in a more thorough site survey and a well-designed wireless network. Seventy-five percent of the work for a good wireless network is in the pre-engineering. It creates the road map for all the other pieces

Back 968

Statement: Infrastructure connectivity

Front 969

Security expectations

Back 969

Consult network management personnel of the organization and enquire about data privacy and encryption which need to be implemented

installing WIDS or WIPS to safegaurd against wireless attacks

Industry specific regulations need to be taken into account like HIPAA, GLB, PCI

Taking all these into consideration check whether existing h/w s/w support these requirements if not recommend purchasing new one which does support

Front 970

Guest access

Back 970

whether guest access need to enabled

Firewall rules and bandwidth throttling for guest users

Front 971

Documents and reports

Back 971

proper document about facility and network should be obtained

create site survey checklist and adhere the checklist during physical site survey

After physical survey a professional comprehensive final report will be submitted to customer .

The report should contain detailed information on how to install and configure proposed network so that anyone could read our report and understand our intent

Front 972

Documents which need to collected from customer before site survey interview

Back 972

1. Blue print

2. Topographic map or contour map

3. Network topology map

4. Security credentials

5. Survey checklist:

Interview checklist

Installation checklist

Equipment checklist

Front 973

Blue print

Back 973

to record RF measurements taken during site survey , location of h/w placement

if not available with customer, check with original architect, govt offices like city hall,fire dept.

use predictive analysis s/w which takes blueprints in vector graphic format like .dwf or .dwg to create capacity and coverage simulations

Front 974

Topographic map

Back 974

a.ka. contour map

necessary when using bridging calculations like Fresnel zone

display info like elevations, forest cover, streams and other water bodies

Front 975

Network topology map

Back 975

get necessary approval and obtain network topology map to understand customers wired n/w infrastructure for seamless integration WLAN into existing wired n/w

provides necessary info like location of wiring closet, layer 3 boundaries

Front 976

Security credentials

Back 976

meet with facility manager and get necessary approval for badge . As part of survey we may have to move around most of the places

Front 977

Survey Checklists

Back 977

Interview checklist: detailed checklist on questions to be asked to customer

Installation checklist: checklist on installation h/w like AP, antenna type, antenna orientation, mounting devices,power sources

Equipment checklist: checklist of all necessary h/w and s/w tools required during site survey

Front 978

Site survey report

Back 978

final comprehensive report submitted to customer after physical site survey

Contains:

1. Purpose statement: stipulates customer requirements and business justification for the wlan

2. Spectrum analysis: identify potential source of interference

3. RF cell boundaries: define cell boundaries

4. H/w placement and configuration: recommend AP/antenna placement/antenna orientation, channel/channel reuse

pattern/power settings

5: Capacity and performance analysis: application throughput test results

Front 979

Additional reports gave along with site survey report

Back 979

1. Vendor recommendations

2. Implementation diagrams: Wireless topology diagram

tells how wlan is integrated into wired n/w

AP placement, VLANS, layer 3 boundaries all will be defined

3. Bill of Materials(BOM): every single item both s/w and h/w required for the final installation of the wireless network.

includes model number and quantity of each item

includes access points, bridges, wireless switches, antennas,cabling, connectors, and lightning arrestors

4. Project schedule and cost: equipment cost, labour costs, schedule timelines.

5. Security solution recommendations

6. Wireless policy recommendation: assist the customer to create if they don't have one

7. Training recommendations: training session for customer's network personnel and brief training for all end users

Front 980

Vertical market considerations

Back 980

1. Outdoor surveys

2. Aesthetics

3. Government

4. Education

5. Healthcare

6. Hotspots

7. Retail

8. Warehouses

9.Manufacturing

10 Multi Tenant buildings

Front 981

Outdoor Surveys

Back 981

calculations like Fresnel zone, earth bulge, free space path loss, link budget, and fade margin are required

equipments should be kept in NEMA-rated enclosure units to protect from weather conditions like lightning, snow and ice, heat, and wind

if tower mount antennas are using get approval from regulatory authorities

if tower is 200 ft above ground level or its a roof mount with 20 ft above high roof level get approval from FCC and Federal Aviation Agency FAA

Front 982

Aesthetics

Back 982

conceal access points from sight.

extremely important in retail and hospitality industry

Front 983

Government

Back 983

security is the major concern

get proper approval for identification badge or pass before conducting site survey

Front 984

Education

Back 984

high density environment

h/w must be properly locked to prevent from theft and hampering

class room wall attenuate RF signals fast. Proper coverage consideration has to be taken care of

Front 985

Healthcare

Back 985

interference from medical equipments is a major concern

A thorough spectrum analysis survey using a spectrum analyzer is extremely important

VoWifi, RTLS are commonly used in hospitals

Healthcare applications used in handheld devices like smartphones, ipad should also be considered

Long hallway, multiple floors, fire safety doors, reflective materials, concrete construction, lead-lined x-ray rooms, wire mesh safety glass are some of the physicalconditions that you will encounter during the survey.

Front 986

Hotspots

Back 986

wireless Internet access for their customers

captive portal solution is required

Front 987

Retail

Back 987

interference sources: baby monitors, cordless phones operating in ISM band kept in display

Multipath sources: storage rack, bins ,inventory

coverage is more important than capacity

retail analytics, wireless connectivity to barcode scanners, pcs

Front 988

Warehouses

Back 988

coverage is more important than capacity

seamless roaming is mandatory bcoz devices are mobile

metal racks, inventory, indoor chain like fences causes reflection and multipath

directional antennas may be required if legacy a/b/g are deployed

Front 989

Manufacturing

Back 989

same like warehouse in interference and coverage design

heavy machines and robotics might be present. Surveyor should be cautious

some manufacturing plants works with hazardous chemicals proper gear should be worn. AP should be kept in ruggedized enclosures

Front 990

Multi Tenant Buildings

Back 990

major challenge is interference from neighboring office wlan and tenants whose APs are configured at high power and non standard channels

less crowded 5GHz is recommended for deploying

Front 991

hardware may be necessary when installing APs to be used for outdoor wirelesscoverage

Back 991

NEMA enclosure

Patch antenna

Outdoor ruggedized core switch

Front 992

biggest concerns when planning for a WLAN in a warehouse environment

Back 992

coverage, roaming, security

Front 993

possible causes of issues while roaming

Back 993

Clients stations can only hear a –70 dBm signal from one access point.

Clients stations can only hear a –70 dBm signal from multiple access point.

interference from 2.4 GHz portable phones.

Front 994

What roaming issues should be discussed during an interview for a future VoWiFi network?

Back 994

Layer 3 boundaries

Latency

Front 995

Chapter 16 essentials

Back 995

1. Site survey defined

2. Site survey tools

3. Coverage analysis

Front 996

Potential source of interference in 2.4GHz band

Back 996

1. Microwave ovens

2. 2.4 GHz cordless phones, DSSS and FHSS

3. Fluorescent bulbs

4. 2.4 GHz video cameras

5. Elevator motors

6. Cauterizing devices

7. Plasma cutters

8. Bluetooth radios

9 .Nearby 802.11, 802.11b, 802.11g, or 802.11n (2.4 GHz) WLANs

Front 997

potential sources of interference in5 GHz U-NII bands

Back 997

1. 5 GHz cordless phones

2. Radar

3. Perimeter sensors

4. Digital satellite

5. Nearby 5GHz WLANs

6. Outdoor wireless 5 GHz bridges

Front 998

When you are designing for coverage during a site survey, the normalrecommended best practice is to provide for a –70 dBm or strongerreceived signal, which is well above the noise floor.

Back 998

Statement: signal strength for normal wlan deployment

Front 999

When you are designing for WLANs with VoWiFi clients, a –67 dBm or stronger signal that is even higher above the noise is recommended.

Back 999

Statement: signal strength for voWifi deployment

Front 1000

excessive coverage overlap because it can cause frequent roaming andperformance degradation

Back 1000

Statement: coverage overlap

Front 1001

recommended coverage cell overlap for roaming purposes

Back 1001

15 percent to 30 percent

Front 1002

1st AP placement

Back 1002

2nd AP placement

Front 1003

SNR

Back 1003

The SNR is simply the difference in decibels between thereceived signal and the background noise

Front 1004

The recommended SNR for a VoWiFi network is

Back 1004

25 dB or higher

Front 1005

Back 1005

VoWiFi cell recommendation

Front 1006

AP Placement and Configuration

Back 1006

1. Cell edge measurements -RSSI(dBm), SNR(dB), Noise level(dBm)

2. AP location and tx power when survey was conducted

3. Location of all wiring closets

4. carry variety of antennas both omnidirectional and semi directional

Front 1007

Application Analysis

Back 1007

done at the end of survey

Use simulators which provides real world environment such vowifi clients, roaming, bidirectional traffic etc and calculate wlan performance

Front 1008

Back 1008

Using a unidirectional antenna in areas where there aremetal racks, file cabinets, and metal lockers can be advantageous at times because you cancut down on reflections in legacy environment

Front 1009

Back 1009

provide coverage in abuilding by using a combination of both low-gain omnidirectional antennas and indoorsemidirectional antennas,

Front 1010

When conducting a site survey, you should use the same 802.11 access point hardwarethat you plan on deploying. True or False

Back 1010

True

Front 1011

Indoor Site Survey Tools

Back 1011

1. Spectrum analyzer

2. Blueprints

3. Signal strength measurement s/w

4. 802.11 client card

5. AP: both autonomous and lightweight

6. WLAN controller

7. Battery pack

8. Binoculars

9. Flashlight

10. Walkie-Talkies or cellphones

11. Antennas

12. Temporary mounting gear: Bungee cords and plastic ties, mast or tripod which can be moved within the building

13. Digital camera

14. Measuring Wheel or Laser Measuring Meter

15. Colored electrical tape: Stick a small piece of colored tape in location where you mounted AP during site survey so that person who install can easily find the spot and fix AP

16. Ladder or forklift

Front 1012

Calculations needed while performing Outdoor Site Survey

Back 1012

1. Fresnel zone

2. Link budget

3. Fade margin

4. Free space path loss

5. Earth bulging

6. IR & EIRP limitations by the regulatory body of country

7. Weather conditions

Front 1013

Outdoor Site Survey Tools

Back 1013

1. Topographic map

2. Link analysis s/w : predictive modelling tool used with topographic map to calculate fresnel zone, EIRP etc

3. Calculators

4. Maximum tree growth data

5. Binoculars

6. Walkie-talkies or cellphones

7. Signal generator and Wattmeter: to to test cabling, connectors, and accessories for signalloss and VSWR before deployment

8. Variable loss attenuator

9. Inclinometer: to measure height of the obstruction

10. GPS

11. Digital camera

12. Spectrum analyzer

13. High-power spotlight or sunlight reflector

Front 1014

2 types of Coverage Analysis

Back 1014

1. Manual

2. Predictive

Front 1015

Manual coverage analysis

Back 1015

2 types :active and passive

passive: all the measurements like rssi, snr, noise level are collected without connecting client adapter to AP during survey

active: measurements are taken by connecting client adapter to AP during survey. Ping is used to connect low level data and check layer 3 connectivity

Vendors recommend both active and passive coverage analysis

Commercial RF survey application can record RF measurements in a building floor plan. They can perform both active and passive coverage analysis

Front 1016

Acommon mistake that surveyors make is to hold the VoWiFi phone in a horizontal positionwhen measuring RF signals during a manual site survey.Reason behind this is

Back 1016

The internal antenna of the VoWiFi phone is typically vertically polarized, and holdingthe phone in a horizontal position results in misleading signal measurements

holding the phone as it will be used, not holding it in a way that creates the best signalreadings.

Front 1017

Predictive coverage analysis

Back 1017

a predictive s/w is used to predict coverage

it takes blueprints and floor plans in .dwf,.dwg,.bmp,.jpg,.tif formats

wlan engineer indicate materials used in floor and s/w have pre programmed attenuation values for various materials like dry wall, concrete, glass

using predictive algorithms and attenuation information it creates forecast models which contains info on :

Number of APs, AP placement, AP power settings, Data rates, channel reuse patterns, coverage cell boundaries

Front 1018

A forecast model isfirst created with the predictive application, and then the site survey engineer conducts amanual site survey to validate the projected design.

Back 1018

Predictive and Manual coverage analysis

Front 1019

Dynamic RF

Back 1019

a.k.a Radio Resource Management(RRM)

it's a self organizing wlan

used in post-deployment environment to make necessary channel and power settings in real time environment

RF information gathered in AP radios are reported back to WLAN controller to perform dynamic RF

It can perform automatic cell sizing, automatic monitoring,troubleshooting and optimization of RF n/w

Front 1020

Wireless Network Validation

Back 1020

to validate Rf coverage and data rates of installed n/w and compare it with values proposed in site survey

Performed by walking through the floor and recording the RF measurements in a floor map

most of the site survey tools can be used but handheld devices provided by vendors like FLuke networks are preferred

Front 1021

Dew point, cloud cover, and thunder have no effect on an 802.11 outdoordeployment

Back 1021

Statement: effect of weather on outdoor deployment

Front 1022

parameters should be validatedduring the manual site survey

Back 1022

1. AP placement and power settings

2. Throughput

3. Coverage boundaries

4. Roaming parameters

Front 1023

Chapter 17 essentials

Back 1023

1. History of PoE

2. PoE devices

3. Planning and deploying PoE

Front 1024

Ethernet has __ pair of wires

Back 1024

4

Front 1025

Out of the 4 pairs 10 and 100 MBps ethernet uses __ pairs to transmit data and __ pairs are unused

Back 1025

2 pairs, 2 pairs

Front 1026

Gigabit ethernet uses all the 4 pairs to transmit data.

Back 1026

Statement: Gigabit ethernet

Front 1027

PoE comes in ___ IEEE standard

Back 1027

IEEE 802.3 af

Front 1028

PoE+ comes in ___ IEEE standard

Back 1028

IEEE 802.3 at

Front 1029

802.3 at

Back 1029

provides 30 watts using 2 pairs of ethernet

supports older devices(Type 1) which requires less power and newer devices (Type 2) which requires more power

Front 1030

PoE components

Back 1030

2 components Power Sourcing Equipment(PSE) and Powered Device(PD)

Front 1031

Powered Device

Back 1031

device which draws power like AP

they are capable of accepting upto 57v in either polarity from PSE known as Mode A or Mode B

PD will reply with Detection signature to PSE, which indicates whether it is in a state to accept power or not and it's 802.3 2012 compliant

If the device is in state in which it will accept power, PD will sent a Classification signature to PSE indication how much power the device need

If the PD doesn't sent classification signature or PSE couldn't identify the device, PSE doesn't how much power is required for the device. At this time device is classified as Class 0 device and PSE provides full power to the device

Type 2 device perform two event physical layer classification or Data link layer classification which allows Type 2 devices to identify whether it is connected to Type1 or Type 2 PSE

Front 1032

Mode A

Back 1032

1,2,3,6

Front 1033

Mode B

Back 1033

4,5,7,8

Front 1034

Power Class 0-3 are considered as Type 1 devices, 802.3 af compliant PoE

Back 1034

Statement: PD classes

Front 1035

Power class 4 is considered as Type 2 device. 802.3 at compliant PoE+

Back 1035

Statement: PD classes

Front 1036

Maximum power of 802.3 af compliant device(PD)

Back 1036

12.95 watts

Front 1037

Maximum power of 802.3 at compliant device(PD)

Back 1037

25.5 watts

Front 1038

PSE

Back 1038

provides power to PD

power supplies is nominal 48 v(44-57 v)

PSE searches for the devices using a Detection signal and PDs has to respond back with a Detection signature

If PSE doesn't receive any response it will withhold power preventing non compliance device from damaging

Amount of power supplied by the PSE is greater than required by PD to accommodate loses from cables.connectors

PSE will continuously monitor connection status with PD to check electrical conditions like short circuit. If the power is no longer required PSE will terminate the power supply to PD

Type 2 devices will perform a two-event Physical layer classification or Data- Link Layer classification, which allows a Type 2 PD to identify whether it is connected to a Type 1 or a Type 2 PSE.

If mutual identification cannot be completed, then the device can only operate as a Type 1 device

Front 1039

Back 1039

PSE power class

Front 1040

2 types of PSE

Back 1040

1. Endpoint

2. Midspan

Front 1041

Endpoint PSE

Back 1041

device that provides ethernet data and power from same device. Normally a 48 port switch with PoE enabled

provides power using 2 methods

Alternative A: PSE places power on data pair

Alternative B: initially used to provide power to 10/100M Ethernet using unused pairs

now Gigabit ethernet ethernet also can be powered putting power on data pairs

Front 1042

Midspan PSE

Back 1042

a.k.a power injector or PoE hub

placed b/w ethernet s/w and PD

acts as a ethernet repeater while adding power to the Ethernet cable

enables us to provide power to existing networks without replacing existing switches

Front 1043

multiport midspan PSE is a.k.a

Back 1043

inline power patch panel

Front 1044

single port midspan PSE is a.k.a

Back 1044

single-port power injector

Front 1045

Maximum distance of Ethernet cable

Back 1045

100 meters or 328 feet

Front 1046

Back 1046

Three PSE solutions

Front 1047

If an AP cannot get the power that it needs, the AP will reboot and try again

Back 1047

Statement: Reboot issue in AP due to inadequate power supply

Front 1048

It is a recommended practice to wait 5-10s after unplugging a PoE enabled device and connecting a non PoE device to prevent it from damaging

Back 1048

Statement:PoE power at Ethernet plug

Front 1049

What will happen in 11n and 11ac capable APs are not provided adequate power

Back 1049

Aps will:

downgrade MIMO capabilities like 3x3:3 will be made to use 1 or 2 transmitter

disable power intensive transmissions like 80MHz and complex modulations

Front 1050

The PD must be able to accept power over either the data pairs or theunused pairs if it is a 10BaseT or 100BaseTX device and over the 1-2, 3-6 data pairs,or the 4-5, 7-8 data pairs if it is a 1000BaseT device.

The PD must also reply to the PSEwith a detection signature.

The PD must accept power with either polarity.

Replying tothe PSE with a classification signature is optional.

Back 1050

PD

Front 1051

The maximum power used by a Class 0 PD is

Back 1051

12.95 W

Front 1052

The maximum power used by a Class 1PD is

Back 1052

3.84 W

Front 1053

The maximum power used by a Class 2 PD is

Back 1053

6.49 W

Front 1054

class and range values

Back 1054

Class 0: 0 to 4 mA

Class 1: 9 to 12 mA

Class 2: 17 to 20 mA

Class 3: 26 to 30 mA

Class 4: 36 to 44 mA

Front 1055

Back 1055

PD power class

Front 1056

Maximum power from PSE

Back 1056

30W

Front 1057

Minimum power from PSE

Back 1057

15.4W

Front 1058

Chapter 20 essentials

Back 1058

1. Mobile Device Management

2. Guest WLAN access

3. Network access control (NAC)

Front 1059

BYOD is

Back 1059

Bring Your Own Device

Front 1060

BYOD refers to the policy of permitting employees tobring personally owned mobile devices such as smartphones, tablets, and laptops to theirworkplace.

Back 1060

Statement: BYOD

Front 1061

MDM Architecture

Back 1061

1. Mobile device

2. WLAN controller

3. MDM server

4. Push notification servers

Front 1062

TCP ports which need to be open in firewall to allow for communications between all of the various componentsof the MDM architecture

Back 1062

AP-MDM: 443

MOBILE-MDM:443

MOBILE-APN: 5223

MOBILE-GCM:443,5223,5229,5330

MDM-APN: 2195,2196

MDM-GCM:443

Front 1063

APN is

Back 1063

Apple Push Notification Service

Front 1064

GCM is

Back 1064

Google Cloud Messaging

Front 1065

MDM Enrollment process

Back 1065

1. Mobile device connects with the AP:

AP quarantines device in walled garden where device has access to only few services like DHCP,DNS, push notification service and MDM server

2. AP checks if the device is enrolled: AP queries MDM server for device's enrollment status. If device is already enrolled MDM server notify AP to release the mobile device if not kept in walled garden

3. MDM server queries LDAP: for user authentication

4. Device is redirected to MDM server: User can open only MDM captive portal for enrollment and cannot proceed further without enrolling

5. Device installs certificate and MDM profile

6. MDM server releases mobile device from walled garden

7. Mobile device exists walled garden

Front 1066

Back 1066

MDM enrollment—initial steps

Front 1067

MDM server—enrollment captive web portal—step 4

Back 1067

Certificate and MDM profile installation—step 5

Front 1068

Back 1068

Mobile device exits the walled garden–final steps

Front 1069

MDM agent application

Back 1069

Used in android device

Apple devices doesn't need MDM agents they have inbuilt MDM agents

MDM agent application from mobile device communicates with MDM server via the Google Cloud Messaging(GCM) service

Front 1070

Information that can be read by MDM server

Back 1070

Device name

serial number

capacity

battery life

apps installed on device

Front 1071

Information that cannot be read by MDM server

Back 1071

SMS

Personal emails

Calendars

Browser history

Front 1072

Mobile device which are enrolled with MDM server can be managed remotely through push notification service like APN or GCM even though they are not connected to corporate WLAN

Back 1072

Statement: MDM server-Mobile device communication

Front 1073

Over the air management

Back 1073

1. Admin make changes to MDM configuration in MDM server

2.MDM server contacts push notification server

3. Push notification server contacts enrolled mobile device and sends a message to contact MDM server over the internet

4. Mobile device contacts the MDM server

5. MDM server sends configuration changes to mobile device

Front 1074

Remote actions that a MDM admin can perform

Back 1074

1. Configuration changes

2. Changes in device restrictions

3. Deliver a message to device

4. Lock the device

5. Wipe the device

6. Make application management changes: Application can be purchased and pushed to devices silently , eBooks can also be managed and distributed to mobiledevices via an MDM platform.

Front 1075

Wi-Fi Client Onboarding

Back 1075

give the customer an inexpensive and simple way toprovision mobile devices onto the secure corporate SSID

Over-the-air provisioning is used to install Wi-Fi client profiles configured with the corporateSSID and security settings

Front 1076

Guest WLAN access

Back 1076

1. Guest SSID

2. Guest VLAN: a unique VLAN for segmenting guest traffic from corporate network

3. Guest firewall policy: to route all guest traffic away from the corporate network infrastructure

Some ports need to be enabled for availing services like DHCP(UDP 67), DNS(UDP 53), HTTP(TCP 80), HTTPS(TCP 443), IPSec IKE(UDP 500), IPSec NAT-T(UDP 4500)

4. Captive web portal: a webportal to register a guest

Front 1077

One of the most important aspects of the captive web portal pageis the legal disclaimer. True or False

Back 1077

True

Front 1078

Guest access moderating

Back 1078

Client Isolation

Rate Limiting,

Web Content Filtering using web filter

Front 1079

Guest credential delivery methods

Back 1079

Text, email, print copy

Front 1080

The parameters within DHCP option 55 create a fi ngerprint that can be used to identifythe operating system of the client

Back 1080

Statement: OS fingerprinting

Front 1081

RADIUS Change of Authorization is defined in RFC

Back 1081

5176

Front 1082

MDM, WLANguest management, and NAC can be deployed as separate components or can be deployedin unison to provide mobile device security management, guest user security, and networkaccess security

Back 1082

Statement:MDM,Guest,NAC

Front 1083

NAC is

Back 1083

Network Access Control

Front 1084

NAC

Back 1084

evaluates capability or state of a computer to determine the potential risk of the computer on the network and to determine level of access to allow

Front 1085

NAC and BYOD

NAC uses various monitoring and fingerprinting techniques to identify different devices so that access can be controlled

Back 1085

A NAC server will use system health information, as reported by a posture agent, to identify if the device is healthy.

DHCP fingerprinting is used to help identify the hardware and operating system.

RADIUS attributes can be used to identify if the client is connected wirelessly or wired, along with other connection parameters. RADIUS CoA is used to disconnect or change the privileges of a client connection.

Front 1086

methods that can be used to provision a root certificate onto Wi-Fi clientsthat function as 802.1X supplicants

Back 1086

1. GPO

2. MDM

Front 1087

resources can a mobile client reach while quarantinedinside a walled garden

Back 1087

1. DHCP

2. DNS

3. MDM server

Front 1088

methods that can be used by a captive web portal to redirect a user tothe captive portal logon page

Back 1088

1. HTTP redirection

2. IP redirection

3. DNS redirection

Front 1089

In order to initially identify, set his permission and calculate the capability of a user should have on the network, the NAC server uses

Back 1089

1. Posture

2. DHCP fingerprinting

3. RADIUS attributes