Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

(Its the) Final Finals > 221 Final > Flashcards

221 Final Flashcards

Remember to also (briefly) study the midterm notes if you care enough to do so. I do not.

1
Q

What is the best practice recieved signal strength?

Lect 13

A

-70 is the minimum acceptable recieved signal strengh, however higher would be considered a better quality signal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the required recieved signal strength for Voice over Wi-Fi?

Lecture 13

A

-65 dBm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

compare different 2.4 GHz data rates to their associated recieve sensitivity.

Lecture 13

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does the recieved signal of -70dBm relate to the noise floor?

Lecture 13

A

-70dBm is well above the noise floor, which allows it to avoid corruption.

The lower the Signal-To-Noise-Ratio (SNR) the higher chance that the singal will become corrupted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some reccomended Signal to Noise Ratios for different types of traffic?

Lecture 13

A
  • 20 dB or greater for basic access
  • 25dB or greater for voice-grade WLAN
  • 29dB or greater to use 256 QAM
  • 35 dB or greater to use 1024 QAM
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Dynamic Rate Switching?

Lecture 13

A

Dynamic Rate Switching is the process APs and client radios use to adjust data rates based on defined sensitivity thresholds.

Due to devices moving unkown distances from access points, AP’s can upshift or downshift their data rate to adjust to the distance of a connected device.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Transmit Power Control (TPC)?

Lect 13

A

TPC is supported by most APs and some clients.

This allows devices to adjust their power to match the transmit power of an associated AP.
Reduces contention interference caused by other clients.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe Roaming Thresholds

Lect 13

A

Roaming Thresholds are values that are set on client devices which decide which access point to establish a connection to.

When a device is roaming, and it is initially connected to AP A, it has a connection that is GREATER than the roaming threshold. Once it moves to an area where the signal strengh has dropped BELOW the roaming threshold value, it begins to search for another AP and attempt roaming.

If AP B has a signal strength within the threshold, it will facilitate a connection with AP B instead of AP A.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe Coverage Overlap, Primary, and Secondary Coverage.

Lect 13

A

Coverage Overlap occurs when primary and secondary coverage from 2 Wi-Fi APs overlap from the perspective of a Wi-Fi Client.

Primary Access Points and Secondary Access Points both need to be heard from a client station at a specific RSSI. The Primary AP provides the network access, and the Secondary is a backup in case the primary goes down or becomes out of range.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 non overlapping 2.4GHz channels?

Lect 13

A

1, 6, and 11.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the Channel Reuse Design Pattern

Lect 13

A

Channel Reuse design is used to prevent overlapping channels. This allows for multiple access points to have overlapping coverage without channel interference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Adjacent Cell Interference?

lect 13

A

Adjacent Cell Interference is the result of improper channel design. All channels are placed adjacently, and overlapping coverage cells have an overlapping frequency space.

To put it plainly, different channels are grouped so close together, that they create RF interference with eachother.

This results in layer 2 retransmissions, data corruption, and performance loss.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an important consideriation to make when deploying the channel reuse pattern?

Lect 13

A

When deploying the channel reuse pattern design, you always need to remember to think 3 dimentionally.

If you are deploying in a building with multiple floors, you need to remember that the channels of the APs on the floors below and above you.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Co-Channel Interference? (CCI)

Lect 13

A

Co-channel interference is an issue that occurs when all access points are using the exact same channel.

This creates an issue due to the half-duplex nature of APs. If one AP is transmitting, all APs that can hear it on the same channel with defer transmissions. APs will have to wait much longer to transmit because they are waiting for their turn.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

L

How many channels are used in the 5GHz reuse design?

Lect 13

A

The channels used are dependent on the region the deployment is placed in, however the rule of thumb is to use as many channels as possible.

Commonly, 8, 12, 17, 22 or more channels may be used for the reuse pattern.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe some best practices associated with the 5GHz channel design.

Lect 13

A
  • First, only use channels that are legally available in your region
  • Keep adjacent cells at least 2 channels apart, and don’t use adjacent frequencies
  • If 2 APs are transmitting the same channel, keep them at least 2 cells of coverage space away from eachother.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is channel bonding?

Lect 13

A

CHanel bonding is the 802.11n technology of combining to 20MHz channels into a larger 40MHz channel.

This effectively allows for doubling the frequency bandwidth of connections by combining channels when possible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe some of the issues associated with channel bonding.

Lect 13

A
  • Bonding results in a +3dB increase to the noise floor.
  • Lower modulation data rates end up being used
  • Increases the odds of CCI occuring.
  • May degrade performance.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Adaptive RF?

Lect 13

A

Adaptive RF is the usage of Radio Resource Management (RRM) to automatically adapt power and channel configurations in Access Points.

RRM provides automatic cell sizing, monitoring, and optimization of the environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is density used when discussing capacity design?

Lect 13

A

High Density (HD) and Very High Density (VHD) are terms used when discussing capacity design and planning for a WLAN.

High density is a term used to describe almost all wireless environments that contain numerous users with multiple devices.

Very high density are environments with large numbers of people condensed in a single open area (think auditoriums, gynmasiums, cafeterias). The areas usually lack walls that provide attenuation.

Ultra High Density is an environment with thousands of users and devices all inside of the same space. (Airports, stadiums)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What questions do you ask when determining how many clients can use a single access point?

Lecture 13

A

The number of clients per AP depends on:
* What type of applications they are using?
* What type of clients and devices are being used?
* How many clients and devices are in a single network?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Compare the required throughput to associated applications.

lect 13

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the difference between throughput and data rates?

Lect 13

A

Data rates are not the same as TCP/UDP throughput.

Medium contention protocols CSMA/CA consume most of the available bandwidth.

I guess data links rely on the quality of the connection ( distance, interference, attenuation, etc)

Kevin gave me no usable information for this slide. I tried my best lol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How many APs should be placed inside of a room?

Lect 13

A

It depends on the room

Its common to place one AP per room, but sometimes that is not needed or is overkill.
this is the second slide that has this as the answer I am trying my best guys.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is Band Steering?

Lect 13

A

Band Steering encourage dual band client radios to connect to a 5GHz AP instead of a 2.4GHz AP.

This allows 5GHz enabled client devices to take advantage of the 5GHz benefits without explicitly connecting to a 5GHz network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe how load balancing works on APs.

Lect 13

A

IT depends on the vendor, but generally:

When a client tries to connect to an AP, an association request frame is sent. If the AP is already overloaded, the association request is deferred back to the client.

Once the client has attempted to connect and has been denied, It should attempt to communicate with a different nearby AP with a lesser client load.

This will hopefully result in a balanced network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe airtime consumption.

Lect 13

A

Airtime consumption is the result of RF being a half duplex medium.

Only one radio can transmit on a channel at a single point in time, so every client device takes turns consuming airtime.

Airtime consumption can be reduced by disabling lower data rates, and having multiple SSIDs associated with an AP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Describe the Software Defined Radio (SDR) Dual 5GHz design.

Lect 13

A

Using SDRs to have a fixed 5GHz radio with dual-frequencies is a growing trend in WLANs.

SDR allows the AP to function as either a 2.4GHz or 5GHz radio. This means that a single AP can either offer both at the same time, or can offer 5GHz on 2 seperate channels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why shouldn’t you mount APs inside of hallways?

Lect 13

A

Mounting APs in hallways can be easier to do due to existing infrastrucure, however it creates CCI and does not attequitely cover all the rooms surrounding the hallway.

30
Q

Describe BYOD.

Lect 14

A

BYOD policies define how employees or users of a wireless network may access a corporate WLAN using their own personal devices.

A mobile ddevice management (MDM) solution can help with onboarding personal mobile devices as well as company issued devices into a network.

31
Q

Name some common MDM solution vendors.

Lect 14

A
32
Q

What are the four main components of MDM architecture?

Lect 14

A
  1. Mobile devices - Not allowed into the corporate network until an enrollment process is completed and an MDM profile is installed. Specific restrictions can be enforced on a device once it’s enrolled.
  2. AP / WLAN Controllers - Govern all access between Wi-FI and devices. The APs can quarantine devices that are not yet part of the MDM.
  3. MDM Servers - REsponsible for enrolling and managing client devices and their access.
  4. Push Notification Servers - Allow for remote management of mobile Wi-Fi Devices.
33
Q

What are some benefits of enabling WLAN guest access?

Lect 14

A
  • Improves productivity for customers and contractors who often need internet acces to accomplish their duties.
  • Customer Loyalty will be gained by having free and secure guest wifi access.
34
Q

Name some common best practices for guest WLAN access.

Lect 14

A
  1. Wireless users should connect to a seperate guest SSID with different security policies than an employee SSID.
  2. Guest networks should be placed in a seperate, unique VLAN tied to a completely different subnet than the employee network.
  3. A captive web portal should be used to accept guest login credentials and provide a legal disclaimer.
  4. A From-Access guest firewall policy is the most important component of guest access management.
  5. Guest networks should also exist and be isolated inside of a DMZ. Traffic from the network should be transported through a VPN tunnel at the edge of the network into the DMZ.
35
Q

Describe some guest firewall best practices.

Lect 14

A
  1. Guest firewalls should have a seperate policy that prevents guest user traffic from getting anywhere near the company network infrastructure.
  2. Should be much more restrictive than other firewall policies.
  3. SMTP should be blocked to prevent spam travelling through the guest WLAN.
  4. Ports that should be allowed through the guest firewall include DHCP, DNS, HTTP, HTTPS, IPsec, NAT-T, ANd IPsec IKE.
36
Q

What are some characteristics of Captive Web Portals?

Lect 14

A

Captive Web portals are usually used to authenticate guests entering a guest network.

Effectively, they turn your web browser into an authentication service.

Can be integrated through most WLAN vendors, or can be created via a standalone server or cloud service.

37
Q

What is client isolation?

Lect 14

A

Client isolation is a feature that allows WLAN access points / controllers to block wireless clients from direct communication with others on the same wireless VLAN.

This is used to prevent peer-to-peer attacks between guest users.

38
Q

What is rate limiting?

lect 14

A

Rate limiting is the process of throttling the bandwidth of user traffic either on the SSID level, or the user level.

This allows you to create a usable connection speed for a larger number of users.

39
Q

Compare and contrast the different methods of guest registration.

Lect 14

A
  • Self Registration - Relies on the guest users to register themselves through a captive portal or kiosk.
  • Employee Sponsorship - Requires an employee email address to be entered. This employee will then sponsor the user by either accepting or rejectiong the connection request.
  • Social Login - Guests are required to provide authorization through an associated social media account.
40
Q

What are the 5 tenets of WLAN troubleshooting?

Lect 15

A
  1. Follow Troubleshooting best practices (LMAO)
  2. Move up the OSI Model
  3. Most Wi-Fi problems are client issues
  4. Wi-Fi performance problems can be avoided through proper WLAN design
  5. Wi-Fi Always gets the blame (WHAT DOES THIS MEAN)
41
Q

List and define troubleshooting best practices.

Lect 15

A
  • Identify the issue (ask questions)
  • Re-produce the problem
  • Locate and isolate the cause
  • Create a plan for solving the issue once identified
  • Implement the plan
  • Once the plan is put in place, verify that your solution worked
  • Document the problem and what you did to fix it
  • Provide feedback to the user who brought up the issue.
42
Q

What questions should be asked to identify network problems?

Lect 15

A
  • When is the problem happening?
  • Where is the problem happening?
  • Does the problem affect one or more clients?
  • Does the problem reoccur or did it only happen once?
  • Did you make any recent changes to your device?
43
Q

What layers of the OSI model should you check when troubleshooting Wi-Fi issues?

Lect 15

A
  1. Physical layer
  2. Data link Layer.

These layers contain Wi-Fi RF and configuration, drivers, WLAN security, WLAN design, VLANs, Physical APs and connections, and more.

44
Q

Describe some possible client Wi-Fi issues.

Lect1 5

A
  • Is the radio on? Try to disable / enable the WLAN NIC.
  • Are the drivers up to date?
  • Are there any exisitng compatability issues?
  • Has the device been properly configured?

Remember that client devices usually are the cause of Wi-Fi issues.

45
Q

What are some common layer 1 wi-fi issues?

Lect 15

A
  • Poor WLAN design
  • RF Interference
  • Transmit power is too high
  • Client radio / driver problems
  • Misconfigured client security settings
  • Firmware issues on APs
  • Power over Ethernet problems.
46
Q

What are some common issues associated with poor WLAN design?

Lect 15

A
  • CCI
  • Layer 2 overhead problems
  • Airtime consumption
  • Data rate issues
  • Channel and power setting misconfiguration.
47
Q

Compare narrowband, wideband, and all-band RF interference.

Lect 15

A
  • Narrowband - occupies a small frequency space and does not cause DoS for an entire band. Can disrupt 802.11 channels which can result in corrupted frames and L2 retransmissions. Eliminated by finding the problematic device and removing it.
  • Wideband - Interference that occurs when a signal has the capability to disrupt an entire frequency band. Same way to resolve as the narrowband.
  • All-Band - Interference with frequency hopping communications like bluetooth. Creates widespread 802.11 corruption. Can be elimated by, you guessed it, doing the exact same thing as the other two!!!!!
48
Q

Describe some problems associated with APs transmitting at maximum power.

Lect 15

A
  • Capacity needs won’t be met properly.
  • CCI and airtime consumption are increased due to unnecessary medium contention.
  • Increase in hidden node issues.
  • Increase in roaming problems.
49
Q

Describe some characteristics of firmware bugs.

Lect 15

A

Older firmware and drivers cause connectivity issues through bugs. Updating APs can also cause unexpected bugs and performance problems.

Using change management processes can prevent firmware bugs from occuring.

enjoy the spongebob ptsd.

50
Q

Name some common problems caused by Layer 2 errors

Lect 15

A
  • Roaming Issues - Can be caused either by drivers on client devices, or by poor WLAN design.
  • Layer 2 retransmissions / retries - Because RF is half duplex, there is no way to detect collisions. This can cause multiple retries that bog down the network.
  • Authentication and Association problems
51
Q

How do Layer 2 retransmissions effect VoWiFi?

Lect 15

A

Because Layer 2 retransmissions acause both latency and jitter to increase, it can negatively effect a networks ability to perform VoWifi

Remember that Latency needs to be below 50ms, and Jitter needs to be below 5ms for VoWiFi to function properly.

52
Q

What causes Layer 2 Retransmissions?

Lect 15

A
  • RF interference
  • Low SNR
  • Adjacent cell interference
  • Hidden Nodes
  • Mismatched Power

Most issues with retransmissions are due to bad WLAN design.

53
Q

How do you troubleshoot Wi-Fi issues in Layers 3-7?

Lect 15

A

you dont.
Layers 3-7 do not have any impact on wi-fi performance.

54
Q

What are the aspects of a site survey design interview?

Lect 16

A

Design interviews take place between cusmoers and technicians to determine the needs of the deployment.

55
Q

Name some of the questions that should be asked during the initial site interview.

Lect 16

A
56
Q

Describe the AP on a stick site survey method.

Lect 16

A

AP on a stick is a legacy method for perfomring site surveys.

An AP is temporarily mounted and a walk through site survey is performed to determine the coverage zone. The AP is then moved to a new location and the coverage zone is determined again. This process is repeated until the entire building has been mapped.

Very time consuming and expensive.

57
Q

What is spectrum analysis and why is it needed?

Lect 16

A

Spectrum analysis is a method of measuring the amplitude and frequency of signals.

This can determine how noisy an environment is and can allow for a network to be configured for the specific needs defined by the noise levels.

58
Q

Name some common sources of 2.4 GHz interference.

Lect 16

A
59
Q

Name some common sources of 5GHz interference.

Lect 16

A
60
Q

Describe the steps of the AP on a stick survey process.

Lect 16

A
  1. Place the first AP in the corner of the building. Walk away from it until your signal drops to -70dBm.
  2. Mount another access point in that location and keep repeating the process to define cell boundaries.
  3. Depending on the shape and size of the coverage cell, adjust AP settings as needed.
  4. A client station needs to see at least 2 APs at the desired signal level for roaming to occur.
61
Q

Describe the hybrid survey process.

Lect 16

A

The Hybrid method is similar to AP on a stick, however it uses RF predictive analysis software instead of physical APs.

It uses the APs power along with antenna radiation patters, FSPL, and signal attenuation properties of the walls in the building to accurately predict where APs should be placed in a building.

62
Q

What are the 3 components of the hybrid survey process?

Lect 16

A
  1. Initial site visit - conducted after the interview process, the site is visited to learn about the RF environment that the APs will be operating in.
  2. Predictive design - Using software to model the possible network map and placement of APs.
  3. Validation survey - Conducted after installation, the validation survey is used to verify that the RF coverage and design objectives have been met or exceeded.
63
Q

What are the primary goals of the initial site visit?

Lect 16

A
  1. Spectrum analysis - Attempting to identify devices that are possibly causing RF interference in the Wi-Fi bands. This allows you to either remove the interfering devices, or work around them after installation.
  2. Attenuation Spot Checks - This involves walking around the property and identifying different types of walls and taking RF measurements. This is used to identify how much attenuation will be caused by the walls that are in place in the building.
64
Q

What are the steps associated with the predictive design process?

Lect 16

A
  • Add a floor plan to the design software
  • Add the walls / wall types
  • Assign attenuation values to specific walls
  • Enter a capacity variable (number of clients, types of devices, possible application usage, etc.)
  • Use a modeling software to determine AP placement.
65
Q

What should be validated when performing a validation survey?

Lect 16

A
  • Coverage, RSSI, and SNR
  • Connectivity
  • Roaming capability
  • Security
  • Latency and Jitter (for VoWiFi
  • Capacity and throughput
66
Q

Name some indoor site survey tools.

Lect 16

A
67
Q

What are the 2 objectives of outdoor site surveys?

Lect 16

A
  1. Provide outdoor coverage and access
  2. Bridge WLANs between buildings or across larger geographic areas.
68
Q

Name some outdoor site survey tools.

Lect 16

A
69
Q

Name some important site survey documentation

Lect 16

A

Documentation provided by a cusomer including:
* Floorplans / topographic maps
* Network topology maps
* Security credentials

Checklists including:
* Initial interview checklists
* Installation checklists
* Equipment checklists

70
Q

What are the main / additional site survey deliverables?

Lect 16

A

The main deliverables include:
* A statement of purpose
* A spectrum analysis report
* A coverage analysis report
* AP Placement and recommendations
* Capacity analysis reports

Addional deliverables include:
* Vendor recommendations
* Implementation diagrams
* Project schedules and costs
* Security recommendations
* Wi-Fi Policy recommendations
* Training recommendations

My final kevin flashcard. Never again. I need a drink.

(Its the) Final Finals (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions