CWDP-305 Certified Wireless Design Professional Questions and Answers

Comprehensive and Detailed Explanation:

Multicasting is a network capability that allows a single data stream to be transmitted to multiple recipients simultaneously, which is highly efficient for live video streaming applications. By configuring multicasting in WLAN implementations, bandwidth usage is optimized, and network congestion is reduced, as the same data does not need to be sent individually to each client. Implementing multicast support ensures that all intended recipients receive the video stream with minimal latency and resource utilization.

Comprehensive and Detailed Explanation:

Painting access points (APs) can interfere with their performance and may void the manufacturer's warranty. Most manufacturers advise against painting APs because certain paints, especially those containing metallic particles, can affect radio frequency (RF) propagation and heat dissipation. Additionally, paint can block ventilation openings, leading to overheating, and can cover LEDs or other indicators, hindering maintenance and troubleshooting. Therefore, it's important to consider these factors and consult the manufacturer's guidelines before painting APs.

Extreme Networks

The most accurate method to determine wall attenuation is to perform empirical measurements. First, measure the Received Signal Strength Indicator (RSSI) in free space at a known distance, such as 1 meter (3 feet). Then, place the access point 0.32 meters (1 foot) away from one side of the wall and the measuring device 0.67 meters (2 feet) away on the opposite side. By comparing the RSSI readings from the free space and through the wall, you can calculate the wall's attenuation. This method accounts for real-world variables and provides more accurate data than relying solely on predictive models or manufacturer specifications.

In WLAN design software, defining different “requirement areas” allows the designer to assign distinct RF and performance requirements to different parts of the floor plan. For instance, a voice-critical conference room may require –67 dBm minimum signal strength and a specific SNR, whereas a storage area might only require basic coverage.

From CWDP-305:

“Requirement areas allow WLAN designers to set different RF performance targets such as minimum signal strength, SNR, and data rate for specific parts of the deployment area. This enables tailored design strategies.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Comprehensive and Detailed Explanation:

In 802.11n, theHigh Throughput Long Training Field (HT-LTF)is utilized by the receiver to estimate the MIMO channel characteristics necessary for demodulating spatially multiplexed signals. The number of HT-LTF symbols corresponds to the number of spatial streams being transmitted. These fields are present in bothMixed ModeandGreenfield Modepreambles.

HT-LTF in Mixed Mode:The preamble includes legacy fields (L-STF, L-LTF, L-SIG) for backward compatibility, followed by HT-specific fields including HT-LTFs for MIMO channel estimation.

HT-LTF in Greenfield Mode:The preamble omits legacy fields and consists solely of HT-specific fields, including HT-LTFs, as there is no need for backward compatibility.

After deploying a WLAN as per the design specifications, conducting a post-installation survey is crucial.This survey verifies that the implemented network meets the design objectives, such as coverage, capacity, and performance.It helps identify any discrepancies between the predicted and actual performance, allowing for necessary adjustments to optimize the WLAN.

Comprehensive and Detailed Explanation:

Installing antennas on a 70-foot tower involves working at significant heights, which presents safety risks and requires specialized skills. Therefore:

A. Hiring a certified tower installer:It is essential to employ professionals who are certified and trained in tower climbing and installation to ensure compliance with safety regulations and standards, such as those set by OSHA and ANSI.

B. Special antennas that avoid reflections on the tower poles:While antenna placement is important, standard antennas can be used with proper installation techniques to minimize reflections.

C. APs that are designed to operate above 70 feet:Access points are designed to operate within specific environmental conditions, but the height of installation does not typically necessitate special APs.

D. Special RF cables that will not create loss incurred by the metal tower construction:Standard RF cables are designed to function effectively in various installations; however, proper cable selection and installation practices are important to minimize signal loss.

A Non-Disclosure Agreement (NDA) is a legal contract that establishes a confidential relationship between parties. In the context of WLAN design, it ensures that any proprietary information shared by the customer during the information-gathering phase remains confidential and is not disclosed to unauthorized parties.

Non Disclosure Agreements

The Statement of Work (SoW) outlines the tasks and deliverables of the project but does not address confidentiality.

The Bill of Materials (BoM) lists the required components for the project but does not pertain to information protection.

A Hold Harmless agreement typically pertains to liability and indemnification, not confidentiality.

In a centralized data forwarding architecture, Access Points (APs) tunnel all client traffic to the WLAN controller.The controller then processes this traffic and forwards it to the appropriate destination.During this process, the controller maps the Differentiated Services Code Point (DSCP) values from the client's IP packets to the appropriate IEEE 802.1Q priority tag values.This mapping ensures that Quality of Service (QoS) is maintained across the wired network, allowing switches and routers to prioritize traffic based on these tags.Cisco

Channel 144 in the 5 GHz band is part of the UNII-2 Extended band. Not all 802.11n devices support this channel, as its inclusion came later in the standard's development. Conversely, 802.11ac devices have broader support for 5 GHz channels, including channel 144. Therefore, if the Access Point (AP) is operating on channel 144, 802.11n laptops that do not support this channel will be unable to detect the SSID, while 802.11ac devices will connect without issue.

RSSI (Received Signal Strength Indicator):Higher RSSI indicates stronger signal reception.

Noise Floor:Lower noise floor improves clarity of communication.

SNR (Signal-to-Noise Ratio):A high SNR is required for good throughput and reliability.

A well-designed WLAN will have:

High RSSI (strong signal)

Low Noise Floor (less interference)

High SNR (clear distinction between signal and noise)

From CWDP-305:

“A strong, clean signal (high RSSI, low noise) results in higher SNR, which directly correlates with better performance and fewer retransmissions.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

When working at heights, especially during the installation of Access Points (APs) on high ceilings, safety is paramount.Personal Protective Equipment (PPE) such as hardhats protect against head injuries, high visibility vests ensure that workers are easily seen, and body belts (or harnesses) provide fall protection.These are standard safety measures in such environments.NWExam

The CWDP-305 Official Study and Reference Guide underscores the importance of appropriate PPE:

"Ensure that installation personnel use appropriate PPE, including hardhats, high visibility vests, and body belts, when working at heights."

Disabling legacy 802.11b data rates (such as 1, 2, 5.5, and 11 Mbps) improves efficiency by reducing airtime used for low data rate transmissions. These rates significantly increase channel occupancy time and reduce network throughput. It also helps eliminate backward compatibility modes like protection mechanisms.

From CWDP-305:

“One of the most effective ways to improve efficiency in 2.4 GHz networks is to disable the use of legacy 802.11b rates. This prevents low-rate clients from consuming excessive airtime and reduces the need for protection frames.”

— Reference: CWDP-305 Official Study Guide, ProtocolandSpectrum Analysis Chapter

Comprehensive and Detailed Explanation:

The "Network Card Simul-ation" feature in site survey software allows the simul-ation of RF data as if it were received by a specific client device.This is particularly useful for assessing uplink performance and understanding how different client devices, with varying antenna gains and sensitivities, would perform in the surveyed environment.By simulating different client types, network designers can ensure that the WLAN design accommodates the performance requirements of all intended client devices.

Site survey adapters are often specialized devices with enhanced sensitivity and are calibrated for accurate measurements. In contrast, standard client devices may have varying hardware and driver configurations, leading to differences in RSSI readings. Therefore, it's common to observe discrepancies between survey results and actual client experiences. This emphasizes the importance of considering client device capabilities during WLAN design and validation.

To ensure that Access Points (APs) are installed in the exact locations specified in the design, it's essential to use visual aids and physical markers.Cameras can capture images of the intended installation sites, and marking tools can be used to indicate precise mounting locations on-site.This approach minimizes errors during installation and ensures adherence to the design plan.

The CWDP-305 Official Study and Reference Guide highlights the use of such tools:

"Use cameras and marking tools to document and indicate AP placement, ensuring accurate installation according to the design."

Wi-Fi Multimedia (WMM) is a feature that enables Quality of Service (QoS) on 802.11 networks, allowing for the prioritization of different types of traffic such as voice, video, and data. If WMM is not enabled, the network cannot differentiate or prioritize traffic types, leading to potential performance issues, especially for latency-sensitive applications like VoIP or video conferencing. Therefore, without WMM, 802.11 QoS functionalities are unavailable, impacting the overall efficiency and user experience of the WLAN.

The primary objective of the initial pre-deployment meeting is to communicate the design decisions to the deployment team, ensuring they understand the design documentation.This alignment is crucial for the successful implementation of the WLAN infrastructure as per the design specifications.

The CWDP-305 Official Study and Reference Guide highlights the importance of clear communication during the deployment phase.

Channels 116-124 in the 5 GHz band fall under the Dynamic Frequency Selection (DFS) range, which requires devices to vacate the channel if radar signals are detected. Proximity to airports increases the likelihood of radar interference, leading to potential disruptions in Wi-Fi service.

The CWDP-305 Official Study and Reference Guide advises:

"In environments near radar installations, such as airports, it's recommended to avoid DFS channels (e.g., 116-124) to prevent service interruptions due to radar detection requirements."

In Wi-Fi networks, the IEEE 802.11e amendment introduces Quality of Service (QoS) features, allowing traffic to be categorized into different Access Categories (ACs) to prioritize data transmission. For Voice over WLAN (VoWLAN) applications, it is crucial to prioritize voice traffic to ensure low latency and jitter. The AC_VO (Voice Access Category) is designated for this purpose, providing the highest priority over other traffic types.

Implementing AC_VO ensures that voice packets are transmitted with minimal delay, which is essential for maintaining call quality in enterprise environments.

Elevator shafts and similar structures can create RF “dead zones” due to their highly attenuating materials like metal. In such cases, simply increasing power or gain typically does not solve the issue due to shadowing. The recommended approach is to move APs or install additional APs on the obstructed side.

From CWDP-305:

“Obstructions such as elevator shafts may require re-positioning or the addition of APs to ensure proper coverage. These obstructions can block RF propagation regardless of transmit power or antenna gain.”

— Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting Chapter

Project parameters in WLAN design software typically include requirements and constraints like:

Minimum required signal strength (e.g., –67 dBm for VoIP)

Minimum required SNR

Desired data rate coverage

These are configured before design work begins and guide how AP placement and coverage will be modeled.

From CWDP-305:

“Project parameters such as minimum signal strength, data rate, and required SNR must be defined before the actual placement of access points. These values define the target RF environment.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Any deviation from the RF design plan, including changes in AP placement, can significantly impact the performance and coverage of the WLAN.Therefore, it's crucial to consult the RF designer before making any alterations.The RF designer can assess the proposed changes and determine if they align with the overall network design objectives or if adjustments are necessary to maintain optimal performance.

To validate fast roaming (802.11r), a protocol analyzer is required to capture authentication frames and reassociation frames between APs. These allow you to verify if fast BSS transitions are occurring and if the endpoint is participating in FT.

From CWDP-305:

“Fast BSS Transition (802.11r) validation requires capturing EAP exchanges and reassociation frames during roaming. A protocol analyzer with multiple adapters can monitor channels simultaneously during transitions.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

High gain omni-directional antennas are designed to radiate RF signals uniformly in all horizontal directions, resulting in a circular pattern on the azimuth chart. However, to achieve higher gain, these antennas compress the vertical radiation pattern, creating a flattened, donut-shaped pattern on the elevation chart. This design focuses the energy horizontally, extending the coverage area while minimizing vertical dispersion, which is ideal for environments requiring broad horizontal coverage.cwnp.com

In stadium environments where aesthetics are crucial, installing APs in enclosures under seats or on handrails is a common practice.This approach conceals the APs, maintaining the venue's visual appeal while ensuring optimal wireless coverage.

The CWDP-305 Official Study and Reference Guide discusses the importance of aesthetic considerations in WLAN design and recommends discreet installation methods in public venues like stadiums.

Comprehensive and Detailed Explanation:

High Rate Direct Sequence Spread Spectrum (HR/DSSS) is associated with the IEEE 802.11b standard, which specifies the following physical layer (PHY) data rates:

1 Mbps and 2 Mbps:Achieved using Differential Binary Phase Shift Keying (DBPSK) and Differential Quadrature Phase Shift Keying (DQPSK) modulation techniques, respectively.

5.5 Mbps and 11 Mbps:Achieved using Complementary Code Keying (CCK) modulation, which allows higher data rates while maintaining robustness against interference.

These rates are specific to the 802.11b standard operating in the 2.4 GHz band.

Designing guest access with all guest users tunneled directly into the DMZ has two main advantages: it simplifies the network configuration and it enhances the security of the internal network. A DMZ is a demilitarized zone, which is a separate network segment that isolates the public-facing services from the private network. A DMZ provides a buffer zone between the Internet and the internal network, where potential attacks can be detected and prevented.

By tunneling all guest users directly into the DMZ, the network configuration is simplified because there is no need to segment and filter the guest traffic across the internal LAN. The guest traffic is encapsulated and routed to the DMZ controller, which acts as the anchor point for the guest WLAN. The guest traffic is then decrypted and forwarded to the Internet or the DMZ services. This way, the guest traffic does not mix with the internal traffic, and there is no need to apply VLANs, ACLs, or firewall rules to separate them.

Another advantage of tunneling all guest users directly into the DMZ is that it enhances the security of the internal network. By keeping the guest traffic in the DMZ, the internal network is protected from any potential threats or attacks that may originate from the guest users. The guest users have no visibility or access to the internal network resources, and they are subject to the security policies and controls of the DMZ. The border firewall configuration will not require any additional rules to pass guest traffic to the DMZ controller, because the guest traffic is already encapsulated and tunneled. This reduces the complexity and the risk of misconfiguration of the firewall rules. References: CWNP, CWDP Certified Wireless Design Professional Official Study Guide, Cisco Unified Wireless Guest Access Services, What Is a DMZ Network and Why Would You Use It?, Wireless Guest Access FAQ

Comprehensive and Detailed Explanation:

RF fingerprinting is a method used in WLANs to determine the location of a device by comparing the current signal characteristics (like signal strength and quality) to a pre-recorded database of signal profiles (fingerprints) taken at various locations. This technique allows for accurate indoor positioning without relying solely on signal strength calculations.

Option A:Inverse cube law is not typically used in WLAN location algorithms.

Option B:Free Space Path Loss (FSPL) calculations are more theoretical and less effective in complex indoor environments.

Option D:Clause 16 of the 802.11 standard pertains to mesh networking, not location algorithms.

Web-based applicationsare designed to operate over the internet using web browsers. Each user interaction, such as clicking a link or submitting a form, typically results in multiple communications between the client and server. These interactions often involve the transfer of various resources, including HTML files, CSS stylesheets, JavaScript files, images, and other data.

This pattern of frequent back-and-forth communication can place significant demands on network resources, particularly in terms of bandwidth and latency. When designing WLANs to support web-based applications, it's essential to ensure sufficient capacity and performance to handle these demands effectively.

Comprehensive and Detailed Explanation:

EAP (Extensible Authentication Protocol) messages are encapsulated withinEAP over LAN (EAPOL)frames when transmitted over 802.11 wireless networks. EAPOL operates at the data link layer and is part of the 802.1X standard, facilitating authentication between the client (supplicant) and the authentication server.

A.EAP-Fast is an EAP method, not the transport mechanism.

B.PEAP is another EAP method that encapsulates EAP within a TLS tunnel.

D.EAP-TLS is an EAP method utilizing TLS for authentication.

Conducting a post-deployment survey before all APs are installed—particularly in a multi-floor environment—may yield incomplete results. APs from other floors can influence coverage (due to bleed-through floors), roaming behavior, and channel planning, so the validation should ideally happen after full deployment.

From CWDP-305:

“In multi-floor environments, APs from upper and lower floors contribute to the RF landscape. Validation should wait until all APs are installed to evaluate the WLAN's full performance characteristics.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

Co-Channel Interference (CCI) occurs when multiple APs on the same channel are heard in the same area, even at relatively low signal levels. CCI is not eliminated simply because signals are below −75 dBm. In fact, CCI is a concern even when APs are heard at levels as low as −85 dBm or lower.

From CWDP-305:

“CCI can be problematic even when the signal from neighboring APs is heard at levels between −85 dBm to −93 dBm. Effective channel planning requires minimizing overlap of same-channel signals at or above these thresholds.”

— Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting Chapter

Conducting site surveys in environments like heavy machinery repair facilities presents unique safety challenges. These areas may have hazards such as moving equipment, loud noises, and airborne particles. To ensure personal safety, surveyors must wear Personal Protective Equipment (PPE), which may include hard hats, safety glasses, ear protection, and steel-toed boots.

The CWDP-305 exam objectives emphasize the importance of safety during site surveys, stating the need to:

"Select and use appropriate design methodologies... Cameras; Personal Protective Equipment (PPE)."

nwexam.com

This underscores the necessity of PPE in certain survey environments.

Options like low gain antennas, low power APs, and indoor APs pertain to technical aspects of the survey but do not address the safety requirements of the surveyor.

Comprehensive and Detailed Explanation:

In warehouse environments with large open spaces and obstacles like metallic racks, providing consistent wireless coverage can be challenging. Installing access points (APs) directly in the central area ensures better signal strength and coverage for workers operating in that zone. However, running Ethernet cables to these central locations may exceed the standard 100-meter limit for Ethernet cabling. To overcome this, implementing a wireless mesh backhaul allows the centrally located APs to connect to the network without the need for extended cabling. This approach provides flexibility in AP placement and ensures reliable coverage in the central areas of the warehouse.

The wavelength (λ) of a radio wave is calculated using the formula:

λ = c / f

Where:

c = speed of light (approximately 3 x 10^8 meters/second)

f = frequency in HzScribd

For 802.11ac operating at 5.5 GHz:Quizlet

λ = 3 x 10^8 / 5.5 x 10^9 ≈ 0.0545 meters ≈ 5.45 cm

This approximates to 5.5 cm (2.16 inches).

Jitter and latency are two important metrics for measuring the quality and performance of wireless networks, especially for real-time applications such as voice and video. Latency is the average time taken for a data packet to reach the destination, while network jitter is the irregularity in latency. When the latency is consistently high, it can mean a slow but stable connection. On the other hand, a high jitter means there may be sporadic disruptions or delays in the transmission, which can affect the quality of service and user experience. Jitter is caused by various factors, such as network congestion, interference, routing changes, hardware issues, or packet prioritization. Jitter can be measured by calculating the difference between the latency of two consecutive packets, or by using the standard deviation of the latency of a sample of packets. Jitter can be reduced by using Quality of Service (QoS) mechanisms, such as traffic shaping, queuing, or scheduling, which can prioritize the packets based on their importance and sensitivity to delay. Jitter can also be mitigated by using jitter buffers, which can store the incoming packets and smooth out the variations in latency before delivering them to the application. References: CWNP, CWDP Certified Wireless Design Professional Official Study Guide, Network Jitter - Common Causes and Best Solutions, Network Jitter vs Latency: What’s the Difference and Why Does It Matter, Jitter vs Latency - What’s The Difference and Why it Matters

The Physical Installation Guide is developed during the design phase and delivered to the installation team. It contains detailed AP locations (including mounting heights and orientations), cabling instructions, hardware installation standards, and any specific AP configuration notes needed during physical deployment.

From CWDP-305:

“A Physical Installation Guide provides specific instructions to installers, such as mounting height, orientation, and any environmental considerations. This ensures that APs are installed correctly and according to the design.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Comprehensive and Detailed Explanation:

Supporting over 300 devices with only two APs in a high-density environment like a convention center auditorium is inadequate.Simply adding more APs without a proper design can lead to co-channel interference and other issues.A comprehensive redesign is necessary to ensure appropriate AP placement, channel planning, and capacity to handle the high number of concurrent clients effectively.

Upgrading access points (APs) from 802.11n to 802.11ac can offer higher throughput and improved performance. However, to realize these benefits, client devices must also support the newer standard. If the clients remain on 802.11n, they cannot take advantage of 802.11ac features such as wider channels, higher modulation schemes, and beamforming.

Therefore, the most likely reason for the unchanged throughput is that the clients were not upgraded to support 802.11ac.

The IEEE 802.11-2016 standard specifies two methods for Fast BSS Transition (FT) to facilitate fast and secure roaming:mrn-cciew

Over-the-Air (OTA):The client communicates directly with the target AP to perform the authentication exchange during roaming.

Over-the-Distribution System (Over-the-DS):The client communicates with the current AP, which then communicates with the target AP over the distribution system to perform the authentication exchange.

These methods are designed to reduce the time required for re-authentication during roaming, ensuring minimal disruption to ongoing sessions.

The CWDP-305 Official Study and Reference Guide states:

"802.11r defines two methods for fast BSS transition: Over-the-Air and Over-the-DS, both aimed at reducing latency during client roaming."

Interference primarily affects the receiver's ability to demodulate signals. In a point-to-point link, RF interference occurring at the middle of the link has little to no impact unless it reaches either endpoint. Therefore, the focus must be on minimizing interference at the receivers.

From CWDP-305:

“Interference at the receiver is the key concern in bridge links. The energy must be received cleanly to enable demodulation, so interference near the receiving AP is more critical than in the link’s midspan.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

Comprehensive and Detailed Explanation:

In the "local MAC" variation of the centralized WLAN architecture, all MAC (Media Access Control) functions are performed by the Access Point (AP). A minimal subset of network control is offloaded to the WLAN controller, which also handles management and monitoring functions. This approach allows for more efficient processing at the edge of the network, reducing latency and improving performance.

Comprehensive and Detailed Explanation:

Latency is a critical metric when designing WLANs for VoIP (Voice over IP) applications. High latency can result in poor call quality, including delays and echoes. Industry standards recommend that one-way latency should not exceed 150 milliseconds to maintain acceptable voice quality. Therefore, during site surveys and network design, measuring and minimizing latency is essential to ensure a high-quality VoIP experience.

If a persistent source of interference cannot be removed, the best course of action is to design around it—usually by changing channels to avoid the affected frequencies. This minimizes the impact on WLAN operation while still coexisting with the interfering device.

From CWDP-305:

“If interference is detected during post-deployment validation and cannot be mitigated by removal, channel reallocation is the most effective way to work around the problem without affecting WLAN integrity.”

— Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting

When calculating the total noise figure of cascaded components, Friis' formula is used:

F_total = F1 + (F2 - 1)/G1 + (F3 - 1)/(G1 × G2) + ...

Where:

F_totalis the total noise factor (linear, not in dB).

F1, F2, ...are the noise factors of the individual stages.

G1, G2, ...are the gains of the preceding stages (linear, not in dB).

In this scenario, the amplifier has a gain of 0 dB, which corresponds to a linear gain of 1. A noise figure of 10 dB corresponds to a noise factor of 10. Assuming the cable and filter have negligible noise contributions or are passive components with minimal loss, their impact on the total noise figure is minimal.

Applying Friis' formula:

F_total = 10 + (1 - 1)/1 = 10

Converting back to dB:

NF_total = 10 × log10(10) = 10 dB

For accurate deployment of access points in a multi-floor indoor environment, providing a camera and marking tools is essential. A camera allows the installation team to reference visual cues from the design, ensuring APs are placed in the correct locations. Marking tools help in identifying precise mounting points on ceilings or walls, facilitating adherence to the design plan. These tools, combined with the design documentation, enable the installation team to execute the deployment accurately, maintaining the integrity of the WLAN design.

Comprehensive and Detailed Explanation:

In 802.1X/EAP authentication, the authenticator (typically the AP or controller) communicates with the RADIUS server using a shared secret for mutual authentication.If this shared secret is misconfigured or does not match on both ends, the RADIUS server will reject authentication requests, leading to client association failures.Therefore, verifying that the shared secret is correctly configured and matches on both the authenticator and the RADIUS server is a critical troubleshooting step.Techimike

EAP-TTLS (Extensible Authentication Protocol - Tunneled Transport Layer Security) is an authentication protocol that allows the use of client credentials (such as usernames and passwords) while requiring a server-side certificate. Client-side certificates are optional, making it a flexible solution for environments where deploying certificates to all clients is impractical. This method establishes a secure tunnel between the client and server, ensuring that credentials are protected during the authentication process.

Comprehensive and Detailed Explanation:

Transitioning from a centralized to a distributed data forwarding model can introduce compatibility issues. Specifically:

C.Some APs designed for centralized architectures may lack the necessary hardware or firmware capabilities to support distributed forwarding features, such as local breakout or direct client-to-client communication, leading to potential limitations in functionality.

Centralized data forwarding means all wireless traffic is tunneled back to a central controller, which handles tasks such as filtering, firewalling, and policy enforcement.

From CWDP-305:

“Centralized data forwarding enables consistent policy enforcement and traffic filtering by handling all traffic at the controller rather than at individual APs.”

This approach provides better control and visibility, especially in environments with strict security and traffic management requirements.

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

In Voice over WLAN (VoWLAN) deployments, it's crucial to differentiate between various types of voice-related traffic to ensure optimal Quality of Service (QoS).Real-Time Protocol (RTP) carries the actual voice payload, while control protocols like RTCP manage session control and quality feedback.Assigning distinct priority levels to these traffic types allows the network to prioritize voice payloads appropriately while still handling control traffic efficiently.

When the WLAN controller and APs reside on different subnets, a router is required to facilitate communication between them. The router enables Layer 3 routing, allowing the APs to discover and communicate with the controller across subnet boundaries.

Laptops are more likely to support advanced wireless features such as 3x3:3 Multiple Input Multiple Output (MIMO) configurations and 256 Quadrature Amplitude Modulation (QAM), which are integral to achieving the higher data rates offered by 802.11ac. These devices typically have the physical space and power resources to accommodate multiple antennas and the processing capabilities required for such advanced features.

In contrast, devices like handheld scanners, tablets, USB 2.0 adapters, and mobile phones are often limited to 1x1 or 2x2 MIMO configurations due to size, power, and cost constraints, making them less likely to support 3x3:3 MIMO and 256 QAM.

Comprehensive and Detailed Explanation:

Video-on-demand (VoD) applications are characterized by their need for high bandwidth to stream high-quality video content. However, unlike real-time applications, VoD can tolerate moderate latency and jitter because buffering mechanisms can compensate for these variances. While VoD requires a stable connection with minimal packet loss to maintain video quality, it is less sensitive to delays compared to voice or live video conferencing applications.

Upgrading access points (APs) from 802.11n to 802.11ac can offer higher throughput and improved performance. However, to realize these benefits, client devices must also support the newer standard. If the clients remain on 802.11n, they cannot leverage the advanced features of 802.11ac, such as wider channel bandwidths, higher modulation schemes, and increased spatial streams.

The CWDP-305 Official Study and Reference Guide emphasizes the importance of considering client capabilities during WLAN upgrades:

"When upgrading a WLAN, it's essential to assess both infrastructure and client devices. Upgrading APs without corresponding client support may not yield the expected performance improvements."

Therefore, in this scenario, the most likely cause of the unchanged throughput is that the client devices were not upgraded to support 802.11ac.

PMK caching(Pairwise Master Key caching) is a roaming technology where the access point (AP) stores the PMK derived during the initial authentication of a client station (STA).If the client roams away and then returns to the same AP, the stored PMK allows for a quicker re-association without the need for a full authentication process.

This mechanism enhances roaming efficiency by reducing latency during re-association, which is particularly beneficial for applications sensitive to delays, such as VoIP.

Target Wake Time (TWT) is a power-saving feature introduced in 802.11ax (Wi-Fi 6) that allows devices to negotiate specific times to wake up and communicate, reducing the need for constant listening and thereby conserving battery life. This feature is particularly beneficial for IoT devices and other battery-powered clients.

USB 3.0 interfaces are known to generate RF interference in the 2.4 GHz band due to the high-frequency noise emitted by the differential signaling in USB 3.0 cables and ports. This interference can reduce SNR, especially for devices located close to the USB port.

From CWDP-305:

“USB 3.0 cables and ports can emit broadband noise in the 2.4 GHz band, negatively impacting receive sensitivity and SNR. This can distort measurements during protocol analysis or performance testing.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

When working in elevated environments, such as installing APs on ceilings higher than standard heights (e.g., warehouse or industrial sites), safety becomes a critical priority. According to the CWDP-305 Study Guide, proper personal protective equipment (PPE) is essential and typically includes a hardhat to protect from falling objects, a high-visibility vest to ensure visibility among other workers or moving machinery, and a body belt or harness when working at height. These safety requirements are commonly enforced by OSHA and are also discussed in wireless site survey preparation sections.

The Effective Isotropic Radiated Power (EIRP) is calculated using the formula:

Omni Calculator

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The Things Network

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EIRP (dBm) = Transmit Power (dBm) + Antenna Gain (dBi) - Cable Loss (dB)

The Things Network

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blog.iptel.com.au

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Assuming negligible cable loss, we first convert the transmit power from milliwatts to dBm:

wifinigel.blogspot.com

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Everything RF

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Transmit Power = 25 mW = 10 * log10(25) ≈ 14 dBm

Now, adding the antenna gain:

EIRP = 14 dBm + 3 dBi = 17 dBm

Therefore, the EIRP of the APs in this design is 17 dBm.

Comprehensive and Detailed Explanation:

WPA/WPA2-Personal is typically used in scenarios where:

A.Client devices lack support for 802.1X/EAP, making enterprise authentication methods unfeasible.

C.Devices are provisioned in bulk with shared credentials, simplifying deployment without the complexity of individual 802.1X configurations.

However:

B.High-latency roaming is undesirable; low-latency is preferred for seamless connectivity.

D.Requiring unique access credentials aligns more with WPA/WPA2-Enterprise, which supports individual authentication.

In the context of High-Level Design (HLD) documents within wireless network design, the primary audiences typically include operations teams, designers, and engineering personnel. These stakeholders are directly involved in the planning, implementation, and maintenance of the network infrastructure.

Executives, while important decision-makers, are not the primary audience for HLDs. Instead, they are more likely to engage with executive summaries or business case documents that highlight the strategic and financial implications of the network design, rather than the technical specifics detailed in HLDs.

In wireless networking, various antenna connectors are used, each differing in size and application.The MC (Micro Coaxial) connector is among the smallest, designed for compact devices where space is at a premium.In contrast, RP-TNC (Reverse Polarity Threaded Neill–Concelman) and N connectors are larger, suitable for more robust applications.Therefore, among the options provided, the MC connector is the smallest.

For long-distance point-to-point wireless links, such as those spanning over 1000 yards, directional antennas are preferred due to their focused beamwidth and higher gain.Yagi antennas are a type of directional antenna known for their high gain and narrow beamwidth, making them suitable for such applications.While panel and patch antennas are also directional, Yagi antennas are specifically designed for long-range communications.

To authenticate users against an LDAP database for WLAN access, a RADIUS (Remote Authentication Dial-In User Service) server must be implemented. RADIUS acts as an intermediary between the WLAN infrastructure and the LDAP directory, facilitating authentication requests. When a user attempts to connect to the WLAN, the access point forwards the authentication request to the RADIUS server, which then queries the LDAP directory to verify the user's credentials. This integration ensures centralized authentication and enhances security by leveraging existing directory services.

For long-range point-to-point bridge links, dish antennas are preferred due to their narrow beamwidth and high gain. An 11 dBi dish antenna focuses energy more efficiently in a single direction, which reduces the amount of Intentional Radiator (IR) power needed to meet link budget requirements.

From CWDP-305:

“Dish antennas provide high gain and a narrow beam, making them ideal for point-to-point bridge links over long distances. This minimizes interference and maximizes EIRP efficiency.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

The IEEE 802.11y amendment introduced support for operation in the 3.65–3.7 GHz frequency band, allowing for higher power transmissions up to 20 watts Equivalent Isotropically Radiated Power (EIRP).This enhancement was designed to improve wireless coverage and performance, especially in environments requiring extended range and penetration.

The increased power and frequency range provided by 802.11y facilitate better service in areas where traditional Wi-Fi bands may be congested or less effective.

The control plane in WLAN architectures is responsible for managing and optimizing various network functions to ensure efficient and reliable wireless communication. Key functions include:

Channel Reuse Plans:Determining optimal channel assignments to minimize interference and maximize spectrum efficiency.

Mobility Management:Facilitating seamless client roaming between access points without service interruption.

Transmit Power:Adjusting the power levels of access points to ensure adequate coverage while reducing interference.

Load Balancing:Distributing client connections across multiple access points to prevent overloading and maintain performance.

These functions are critical in both centralized and distributed WLAN architectures to maintain optimal network performance and user experience.

When using controller-based WLANs, configuration profiles (e.g., for SSIDs, VLANs, radio settings, etc.) are defined on the controller and then assigned to APs—often by AP group or based on AP naming convention or location. This enables automatic provisioning once APs connect to the network.

From CWDP-305:

“Prior to deployment, profiles should be configured on the controller and associated with AP groups or individual APs. Once connected, APs will download their configuration from the controller automatically.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

In high-density environments like stadiums and convention centers, the presence of large crowds significantly impacts Wi-Fi signal propagation.Human bodies, composed mostly of water, absorb and attenuate radio frequency (RF) signals, especially in the 2.4 GHz and 5 GHz bands commonly used by Wi-Fi.This absorption leads to reduced signal strength and potential connectivity issues during events when the venue is filled with people.

Designing a WLAN for such environments requires careful consideration of crowd density and its impact on RF signals.Strategies may include increasing the number of access points (APs), using directional antennas to focus coverage, and conducting site surveys during events to assess real-world performance.

In wired networks, VLANs (Virtual Local Area Networks) are used to segment network traffic into separate broadcast domains, effectively isolating traffic for security and performance purposes.Each VLAN operates as its own distinct network segment.

In wireless networks, while VLANs are used to segregate traffic once it reaches the wired infrastructure, the wireless medium itself is inherently a shared medium.This means that, over the air, all wireless clients share the same RF space, and broadcasts are received by all clients regardless of VLAN assignment.Therefore, VLANs in wireless networks do not inherently provide the same level of broadcast domain separation as in wired networks.

Post-implementation deliverables serve to document the final WLAN design, configuration, and layout for the customer’s operational and maintenance teams. The CWDP-305 Study Guide identifies essential deliverables that ensure long-term support, change management, and troubleshooting.

These include:

Floorplans with AP placements and coverage zones

Design documents specifying SSID configuration, channel plans, and power levels

WLAN configuration exports or screenshots for controllers/APs

Inventory lists of installed equipment (serial numbers, models, etc.)

Guides or SOPs for routine WLAN tasks

Providing this documentation is a professional best practice that aligns with design transparency, customer service, and lifecycle management. It enables future audits, upgrades, or expansions while ensuring continuity even if personnel changes.

Lower data rates, such as 1 Mbps, use simpler modulation schemes (e.g., BPSK) which are more robust against noise and require lower signal-to-noise ratios (SNR) for successful reception.This means that frames transmitted at lower data rates can be received over longer distances compared to higher data rates like 54 Mbps, which use more complex modulation schemes (e.g., 64-QAM) that require higher SNR and are more susceptible to signal degradation.

When establishing a long-distance wireless bridge, such as one spanning 13 kilometers, it's crucial to consider the Fresnel Zone, which is the elliptical area around the line-of-sight path between two antennas. Obstructions within this zone can cause signal degradation due to diffraction.

One significant factor affecting the Fresnel Zone over long distances is the Earth's curvature, commonly referred to as the Earth bulge. As the distance between the two points increases, the Earth's surface curves away, potentially intruding into the Fresnel Zone and obstructing the signal path. Therefore, engineers must calculate the Earth's bulge and ensure that antenna heights are sufficient to maintain a clear Fresnel Zone.

While Free Space Path Loss (FSPL), antenna gain, and receiver sensitivity are essential parameters in link budget calculations, they do not directly address the physical clearance required in the Fresnel Zone.

A passive survey is the most appropriate survey type when diagnosing coverage and signal strength issues. It listens to beacons and probe responses to map the RF environment, showing actual signal levels, noise levels, and AP visibility across the site. Passive surveys are particularly valuable for understanding how clients "see" the network when associating.

From CWDP-305:

“Passive surveys are used to validate RF coverage and detect interference. They listen to beacon and other management frames to determine AP coverage areas without needing to associate to a specific AP.”

Active surveys require client association and are more suited for performance-related assessments (like throughput and latency), while predictive surveys are used for pre-deployment modeling.

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

Effective Isotropic Radiated Power (EIRP) is calculated by adding the transmit power (in dBm) to the antenna gain (in dBi).

Transmit power: 25 mW = 14 dBm

Antenna gain: 3 dBi

EIRP = 14 dBm + 3 dBi = 17 dBm

The CWDP-305 Official Study and Reference Guide provides guidance on calculating EIRP to ensure compliance with regulatory limits and optimal network performance:

"EIRP is the sum of the transmitter output power and the antenna gain, accounting for any losses. Accurate EIRP calculations are essential for regulatory compliance and effective wireless design."

In high-density environments with limited DHCP address pools, it's crucial to manage IP address allocation efficiently. Reducing the DHCP lease time to a shorter duration, such as 20 minutes, ensures that IP addresses are recycled more frequently. This approach minimizes the risk of address exhaustion by promptly reclaiming addresses from devices that disconnect or become inactive. While adjusting client timeouts and maximum client limits can help manage network load, they don't directly influence DHCP address utilization.

Comprehensive and Detailed Explanation:

When discrepancies are found between the physical environment and the CAD drawings during a site survey, it's crucial to update the documentation to reflect the current state accurately. Redrawing the portions of the map that have changed ensures that the design and subsequent deployment are based on accurate information, leading to a more reliable and efficient wireless network.

The primary goal of the initial pre-deployment meeting is to ensure that the deployment team fully understands the design documentation, including the rationale behind design decisions. This understanding is crucial for accurate implementation and to address any potential issues proactively.

In environments with low Signal-to-Noise Ratio (SNR), maintaining reliable communication becomes challenging due to increased potential for errors.Receive Diversityis a technique employed to enhance signal reception under such conditions.

Receive Diversity involves using multiple antennas at the receiver to capture the same signal.By combining these multiple received signals, the system can mitigate the effects of fading and interference, effectively improving the SNR.This enhancement leads to better throughput as the likelihood of retransmissions due to errors decreases.

Other options like 64-QAM require high SNR to function effectively, and A-MSDU frame aggregation is more beneficial in high SNR environments where larger frames can be transmitted without significant error.

Comprehensive and Detailed Explanation:

Not all client devices support the full range of 5 GHz channels.Some devices, especially older ones, may only support the lower UNII-1 band (channels 36–48) and not the higher channels like UNII-2 or UNII-3.If the WLAN infrastructure utilizes channels that the client's device does not support, the device will not detect the SSID on those channels, leading to poor or no connectivity in certain areas.This explains the manager's experience of poor RSSI or lack of connection in specific spots, despite the APs functioning correctly.

This issue arises due to partial support for 5 GHz channels by some client devices. Although the infrastructure may use all 25 available 5 GHz channels in the U.S. (spanning UNII-1 through UNII-3 and DFS channels), many older 802.11n tablets and clients only support a subset of these channels—commonly the lower UNII-1 band (channels 36–48). As a result, even though the APs are operational and signal coverage is valid overall, the client may not see or associate with APs operating on unsupported 5 GHz channels such as channels 52–64 or DFS channels (100–144).

This leads to inconsistent connectivity or lack of signal in areas where APs are broadcasting on unsupported channels. The CWDP-305 Study Guide advises taking client capability into account during design validation and includes best practices for mapping expected device support versus operational channel plans.

Among common construction materials, fire-rated steel doors present the highest level of RF attenuation. Steel reflects and absorbs significant RF energy, often reducing signal strength by 10–20 dB or more.

From CWDP-305:

“Fire-rated metal doors and elevator shafts are among the most attenuating structures in a building. These materials reflect and absorb RF signals, severely limiting Wi-Fi propagation.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

Comprehensive and Detailed Explanation:

In environments with highly reflective materials, such as manufacturing facilities, the use of Short Guard Intervals (SGI) can lead to increased inter-symbol interference due to multipath propagation. SGI reduces the guard interval from 800ns to 400ns, which can improve throughput in environments with minimal interference. However, in reflective environments, the shorter interval may not provide sufficient time to mitigate the effects of delayed signals, leading to higher error rates. Therefore, it is recommended to disable SGI on the 2.4 GHz band in such environments to maintain reliable communication.

Maximal Ratio Combining (MRC) is a technique used in MIMO (Multiple Input Multiple Output) systems to improve signal quality by combining multiple received signals. However, 1x1:1 client devices have only one transmit and one receive antenna, making them incapable of utilizing MRC, which requires multiple antennas to combine signals effectively.

The CWDP-305 Official Study and Reference Guide explains:CliffsNotes

"Features like Maximal Ratio Combining, which rely on multiple antennas, are not applicable to single-stream (1x1:1) client devices."

In the 5 GHz band, certain channels like 144 are not universally supported across all devices, especially older 802.11n clients. If the AP is operating on channel 144, and the client's regulatory domain or hardware does not support this channel, the SSID will not be visible to the client.

The CWDP-305 Official Study and Reference Guide notes:

"Client devices may not support all channels in the 5 GHz band, depending on their regulatory domain and hardware capabilities. Channel 144, for example, is not supported by all 802.11n clients."

A WLAN scanner (e.g., inSSIDer, WiFi Analyzer) is a simple, often free or low-cost tool that scans the air for available SSIDs and channels. It is used for basic visibility of neighbor WLANs, including SSID names, signal strengths, and channels in use.

From CWDP-305:

“WLAN scanners are useful for identifying neighboring WLANs, SSIDs, and basic RF characteristics. While not as detailed as professional survey tools, they are sufficient for quick checks.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

Comprehensive and Detailed Explanation:

Passive RFID tags lack an internal power source and rely on energy transmitted from an RFID reader to power up and communicate. In WLAN designs supporting RTLS, passive tags do not directly communicate with the WLAN infrastructure. Instead, they depend on tag readers to capture their information and relay it to the location server. This design consideration is crucial for accurate asset tracking and management.

Comprehensive and Detailed Explanation:

Ensuring high availability in RF design involves strategies that provide redundancy and resilience:

C. Deploy using 100 percent overlap:Overlapping coverage areas between APs ensure that if one AP fails, clients can seamlessly connect to another, maintaining network availability.

E. Use dual spectrums:Utilizing both 2.4 GHz and 5 GHz bands allows for flexibility and redundancy. If one band experiences interference or congestion, clients can switch to the other.

A. Powering APs to maximum powercan lead to increased interference and is not a recommended practice for high availability.

B. HSRP/VRRP protocolsare related to router redundancy and do not directly impact RF availability.

D. Deploying 802.3afrefers to Power over Ethernet standards and, while important for powering devices, does not directly contribute to RF high availability.

In a controller-based WLAN infrastructure, when the Wireless LAN Controller (WLC) and Access Points (APs) reside on different subnets, a router is essential to facilitate communication between them.The router enables inter-subnet routing, allowing APs to discover and communicate with the WLC.

The CWDP-305 Official Study and Reference Guide emphasizes the necessity of proper Layer 3 routing for APs to locate and join controllers across different subnets.

Comprehensive and Detailed Explanation:

Modulation is the technique of varying a carrier signal's properties—such as amplitude, frequency, or phase—to encode and transmit data. This process allows the transmission of information over various mediums, including radio frequencies used in wireless communications.

Option A:Describes spread spectrum techniques, not modulation.

Option B:Is a partial description but lacks the specificity of how the carrier is modified.

Option D:Is a vague statement that doesn't accurately define modulation.