300-425 Designing Cisco Enterprise Wireless Networks (ENWLSD) Question and Answers

 For Stateful Switchover (SSO) to function correctly, the redundancy ports on both the primary and secondary controllers must be directly connected. This allows for the necessary state and configuration information to be synchronized between the two controllers, preventing the secondary controller from entering maintenance mode in the event of a failover.

 In a Layer 1 passive wireless site survey, the chart that indicates the ratio of interference present during the duration of the capture in the 2.4 GHz spectrum is typically a Duty Cycle chart or an Interference chart. These charts display the percentage of time that energy, possibly from interfering sources, is present on a channel. The correct answer would show fluctuations in signal levels over time, highlighting periods where interference might be affecting the channel’s clarity.

 AP groups allow the mapping of specific WLANs (SSIDs) to distinct VLANs for different locations. This design enables clients to be on different subnets based on their building location without modifying the access points’ mode of operation.

Link Aggregation Group (LAG) allows multiple physical ports to be combined into a single logical channel. In the scenario where only one Cisco 9800-40 WLC is available and high availability is required, LAG can be used to manage port redundancy and perform load balancing between APs transparently. This ensures that if one cable fails, the others can continue to carry the traffic without any perceived downtime

For wireless clients to use the 5 GHz band when Client Band Select is enabled, certain conditions must be met. Channel bonding should be enabled on the WLAN to allow for wider channels, providing higher throughput available in the 5 GHz band. The client must receive an RSSI above the minimum threshold set for Band Select to steer them towards the 5 GHz band. Additionally, the client device must be dual-band capable to connect to both 2.4 GHz and 5 GHz bands. Co-channel interference levels and UNII-2 extended channels being enabled offer additional benefits but are not requirements for Band Select functionality. Having 802.11a enabled on WLAN is necessary for any operation on the 5 GHz band but does not specifically relate to ensuring clients use this band under Band Select policies.

References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice)

 When performing a site survey of a large outdoor area, a site survey tool with a GPS module is ideal. The GPS module allows for precise location tracking, which is essential for mapping signal coverage over a large area. This tool can help complete the survey efficiently by automatically recording the location of signal measurements

The Catalyst 9300X-48HX switches support PoE, which can power the 9166 APs. To ensure that all APs run with full functionalities, including PoE, the engineer should connect the APs to all available ports on the stack of two Catalyst 9300X-48HX switches. This will provide sufficient power and connectivity for the APs to operate effectively. References: Cisco Catalyst 9300X switch specifications and PoE requirements for 9166 APs.

Guest anchoring requires mobility tunnels to be established between the foreign and anchor WLCs. For these tunnels to function, the firewall must allow specific ports for communication. UDP port 16666 is the port used for mobility traffic in Cisco wireless networks, and if it is not allowed through the firewall, MPING and mobility tunnels will fail. References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice

 In a mining facility, especially within mine shafts where the environment can be long and narrow, an omnidirectional antenna is typically used for a Layer 2 survey. This type of antenna radiates RF signal equally in all directions, providing coverage along the length of the shaft.

IEEE 802.11ac Wave 2 APs are backward compatible with 802.11a/n clients, allowing these devices to connect and communicate with the newer APs, albeit at their respective maximum supported speeds.

 In environments with high client density, deploying APs for 5 GHz coverage is recommended due to the larger number of non-overlapping channels available, which can support higher data rates and client capacity. Disabling the 2.4 GHz radios on some APs can reduce interference and improve overall network performance.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/86/b_Cisco_Wireless_LAN_Controller_Configuration_Best_Practices.html

To support high availability, the design must include redundant Wireless LAN Controllers (WLCs) to ensure service continuity in case of a failure. Additionally, having a high availability pair with one WLC holding a valid AP count license ensures that all APs can remain connected and services continue without interruption during failover.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-44074

The data path issue between the Cisco Catalyst 9800-CL and AireOS 5520, despite an active control path, is likely due to encrypted mobility being enabled on the AireOS 5520. Encrypted mobility requires both peers to have a matching configuration for encryption, which includes proper certificates and shared secrets. If there’s a mismatch, the control path may be established, but the data path can fail due to the inability to establish an encrypted tunnel.

 Before replacing old APs with IEEE 802.11ac-capable APs, it is crucial to check the software version of the wireless LAN controller. The controller’s firmware must support the newer standards and capabilities of 802.11ac APs. An outdated software version may not support the advanced features and performance enhancements offered by 802.11ac technology, leading to compatibility issues and suboptimal network performance.

References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice.

 Cisco FastLocate technology is part of the Cisco Hyperlocation solution, which enhances location tracking accuracy and refresh rates. Implementing Cisco FastLocate technology can address issues with refresh rates for location updates in a custom mobile app by increasing the number of location data points captured, thus providing more frequent and accurate location updates.

References := AP4800 Hyperlocation Deployment Guide - Cisco

 Large cases of liquid materials can cause higher signal loss compared to dry goods due to the way radio frequency (RF) waves interact with liquid, which can absorb and reflect the signals more than dry materials.

The ‘tracert’ command is used to test connectivity between members of a mobility group by tracing the path that mobility control packets take over the network. This command helps identify any potential issues with the route that the packets are taking, which could affect the ability of guests to connect to the anchor controller in the DMZ. References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice)

To connect multiple wired devices over a workgroup bridge using an autonomous AP, a router is needed to manage the IP addresses and route traffic between the wired devices and the wireless network. The router will act as a gateway for the wired devices, allowing them to communicate with the WLAN. References: Cisco autonomous AP configuration guides and workgroup bridge deployment scenarios.

Setting the Anchor priority for the primary controller to 1 ensures that clients connect to the primary controller first. The Anchor priority is a value assigned to each controller within a mobility group to determine the order in which clients should connect to the controllers. A lower priority value has higher precedence. Therefore, by setting the primary controller’s Anchor priority to 1, it becomes the preferred controller for client connections. If the primary controller fails, clients are then pushed to the secondary controller, which should have a higher Anchor priority value.

 In an office environment with cubicles, signal propagation is most commonly affected by absorption. This is because the materials used in cubicle walls, such as fabric and other dense substances, tend to absorb the radio frequency (RF) signals used in WLANs, leading to attenuation.

For optimized roaming across multiple Wireless LAN Controllers (WLCs) with Cisco 8821 phones, configuring mobility groups between WLCs allows for seamless roaming and sharing of security contexts. Additionally, using Cisco Centralized Key Management (CCKM) for authentication reduces the time required for re-authentication during roaming, providing a more efficient transition between access points3

Access points can be assigned different failover priorities to determine the order in which they will failover in the event of a primary controller failure. An access point with priority 1 is given the highest priority level and is considered critical. This means it will failover before other access points with lower priorities, ensuring that the most critical areas remain covered.

When the mobility tunnel is not operational for the data path, it is essential to validate the network’s firewall settings. Firewall port 16666 must be open to allow mobility control messages to pass through, and firewall IP protocol 97 (EtherIP) must be permitted to enable the encapsulation of IP within IP, which is necessary for the data path of the mobility tunnel. Ensuring these firewall settings are correctly configured is critical for facilitating inter-controller roaming and operational mobility tunnels.

In Cisco WLC version 8, the need for separate WPlus licenses has been eliminated as all features that were previously part of the WPlus license are now included in the Base license. This consolidation simplifies licensing management and ensures that customers have access to all necessary features without requiring additional licenses. References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice)

For a wireless voice deployment, Cisco recommends that the edge of the cell should have a signal strength of -67 dBm to ensure reliable voice quality and seamless roaming capabilities.

 The most effective way to address the issue is to resurvey the areas with the correct survey devices. This ensures that the design accurately reflects the performance characteristics of the specified access points for each area type, leading to a more reliable and efficient wireless network design tailored to each environment’s specific needs.

Mobility domains and mobility groups are concepts used in Cisco wireless networking to manage client roaming and controller interaction. When Wireless LAN Controllers (WLCs) are part of the same mobility domain, they share a common database, allowing them to communicate and facilitate seamless client roaming. A mobility group is a subset of this domain, where specific WLCs work together more closely to share client context and security credentials. This ensures that when a client roams from one access point (AP) to another across different controllers, the authentication and security context are maintained, allowing for a seamless transition without the need to re-authenticate. The mobility group also manages AP fail-over between controllers, ensuring clients can maintain their connections even if their current AP fails or becomes unreachable.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-0/configuration-guide/b_cg80/b_cg80_chapter_010011.html

 For mobility between two buildings with one controller at each site, CAPWAP data and control traffic must be able to pass between controllers. CAPWAP control messages use UDP port 5246 while CAPWAP data messages use UDP port 5247; therefore, these ports must be open to allow inter-controller communication for seamless mobility. References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice)

 The AP fallback feature is designed to allow access points to return to their primary controller after they have connected to a secondary controller due to a failure or connectivity issue with the primary. This setting ensures that once the primary controller is back online, the APs will recognize it and re-establish their connection as per the original network design. This feature is crucial for maintaining the intended controller hierarchy and ensuring seamless wireless network operation.

The voice readiness tool in Cisco Prime inspects the network against a dBm range that is suitable for voice over Wi-Fi. The range of -72 to -67 dBm is considered optimal for voice applications, ensuring clear audio quality and minimal packet loss.

https://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/infrastructure/34/user/guide/bk_CiscoPrimeInfrastructure_3_4_0_UserGuide/bk_CiscoPrimeInfrastructure_3_4_0_UserGuide_chapter_01010.html

 The Cisco 8540 Wireless Controller is designed for large enterprise and high-density environments. It has the capacity to manage up to 6000 access points, making it suitable for a multicampus architecture that needs to accommodate 4500 access points. Its high availability features ensure that all access points can be supported on one controller setup with minimal downtime.

Voice over wireless roaming is sensitive to delays and interruptions. Full reauthentication, as mentioned in option A, can cause noticeable gaps in a voice conversation because it requires time to re-establish security credentials. This process can interrupt the seamless experience expected in voice communications. Option E is also correct because roaming with only 802.1x authentication indeed requires full reauthentication, which can introduce significant delays affecting voice quality. References: For more detailed information, refer to the CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide.

https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/vowlan/41dg/vowlan41dg-book/vowlan_ch5.html

To focus the coverage heat map on the desired coverage, the engineer should use the RSSI slider to set the heat map to the desired cutoff filter. This action will adjust the display to show only the signal levels that meet or exceed the specified RSSI value, effectively filtering out weaker signals and highlighting areas with sufficient coverage. References: Designing Cisco Enterprise Wireless Networks (ENWLSD 300-425)

 To predict the number of APs needed to support approximately 300 wireless devices on a new floor with an 802.11ac network, the Demand Settings in the Cisco Prime Infrastructure Planning Tool must be adjusted. This setting allows the planner to specify client density and throughput requirements, which are crucial for determining the correct number of APs.

An RSSI value of -77 dBm is within the range that a 5 GHz radio can receive and decode, provided it’s not below the RX-SOP threshold set for the RF profile. Since the RF profile is set to Medium for 802.11a, which operates in the 5 GHz band, the AP’s 5 GHz radio will decode the frames.

Micro cells with reduced power levels are suitable for environments with a high concentration of wireless clients and multimedia applications, as they help manage interference and allow for better roaming capabilities. References: ENWLSD 300-425 Official Cert Guide.

 Adjusting the RX-SOP (Receiver Start of Packet Detection Threshold) can help to control cell size by making APs less sensitive to low-level signals, thus requiring clients to be closer to the AP to connect, which can ensure they connect to the nearest AP with the highest data rates.

 Cisco Hyperlocation requires a high degree of accuracy in client location tracking. A recommended cell overlap of 50% ensures that client devices are consistently within the range of multiple access points, which improves location accuracy and reliability. References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide.

For Cisco Wireless LAN Controllers (WLCs) to operate in High Availability (HA) with Stateful Switch Over (SSO), they must be connected through a Redundancy Port (RP). This dedicated port is used for synchronization of stateful information and ensuring seamless failover without service interruption.

FlexConnect mode is ideal for branch offices and remote locations where it’s necessary to minimize wireless traffic tunneled back to the Wireless LAN Controller (WLC). In FlexConnect mode, APs can perform client authentication locally and bridge traffic onto the local network. References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide.

For pervasive coverage in an oil terminal that supports casual web and email traffic over 5 GHz, disabling lower data rates can help improve overall network efficiency. Lower data rates can cause the network to slow down because they take up more airtime. By disabling rates below 24 Mbps, the APs can focus on providing higher throughput for users. Keeping the power assignment as auto allows the APs to adjust their power levels dynamically for optimal coverage and client performance

 Enabling control plane encryption on the wireless controller is crucial for establishing a secure mobility tunnel between the wireless controller and the anchor controller. Control plane encryption ensures that the signaling and management traffic traversing the mobility tunnel is encrypted, providing a secure channel for guest access authentication and authorization processes. This is particularly important when the anchor controller is deployed within a DMZ, as it is exposed to potential external threats. The Cisco Catalyst 9800 Series wireless controller supports control plane security features that can be leveraged to secure the mobility tunnel and ensure the integrity and confidentiality of the control traffic.

The 9800 Series Wireless Controller uses CAPWAP tunnels to encapsulate and transport both control and data traffic between access points and the controller. This allows for centralized management and control while also enabling efficient data forwarding.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/b_wl_16_10_cg/mobility.html

The 5 GHz band is recommended for voice over wireless due to its wider channel bandwidths, allowing for higher data rates. Setting the cell boundary at -67 dBm ensures sufficient signal strength for reliable voice communication. References: CCNP Enterprise Wireless Design ENWLSD 300-425 Official Cert Guide.

FlexConnect APs must be in a FlexConnect group to support 802.11r Fast Transition (FT). This grouping allows for local authentication and key management, which are necessary for fast roaming methods that improve voice quality and wireless IP phone performance during roaming.

References: The official Cisco FlexConnect configuration guide 

 When collapsing all controllers to a single cluster in a central location, one must consider the availability of channels across different regions. Regulatory domains vary globally, and certain channels allowed in Europe may not be available or legal in other parts of the world. This can affect the consistency of wireless coverage and performance.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/86/b_Cisco_Wireless_LAN_Controller_Configuration_Best_Practices.html

When Client A roams from AP1 on WLC1 to AP2 on WLC2 across different subnets, this is considered a Layer 3 roam. Unlike Layer 2 roaming where the client’s database entry moves with them, in Layer 3 roaming, the client’s database entry is copied to the new controller (WLC2). This ensures continuity of service as Client A transitions between access points managed by different wireless LAN controllers. References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide Premium Edition and Practice)

 Mobility tunnels between Cisco Wireless LAN Controllers (WLCs) use UDP port 16666 for control messages and UDP port 16667 for data traffic. If EPING is failing, it indicates that the necessary ports are not open. Allowing UDP port 16666 through the firewall would enable the control messages required for establishing the mobility tunnels.

 For optimal Voice over WLAN (VoWLAN) design, a higher data rate is preferred to ensure quality of service and reliability. -67 dBm is a commonly recommended signal level for VoWLAN, and 802.11an, which operates in the 5 GHz band, is capable of supporting higher data rates compared to 802.11bgn, which operates in the 2.4 GHz band. The 5 GHz band is less crowded and prone to interference, making it suitable for high-speed data and voice applications.

 Optimized roaming is a feature that helps manage the client’s roaming behavior by disassociating clients with a signal strength below a predefined threshold. This feature is designed to prevent clients from sticking to an AP with poor connectivity, which can lead to suboptimal performance. If the BSS Transition Management query is causing the client to roam and the disassociation imminent feature is not enabled, it indicates that optimized roaming is likely enabled, prompting the client to seek a better AP connection.

A Patch antenna should be used to provide wireless coverage on the perimeter of a building while minimizing signal leakage. Patch antennas have a directional radiation pattern that can be focused along the perimeter.

https://www.cisco.com/c/en/us/td/docs/routers/connectedgrid/antennas/installing-combined/industrial-routers-and-industrial-wireless-antenna-guide/ANT-MP-INT-OUT-M.html

For a point-to-multipoint mesh network site survey, configuring the Rx power and Tx power is essential. Rx power will determine the sensitivity of the AP to incoming signals, which is crucial for understanding the reach of each mesh point. Tx power settings will influence the strength of the signals transmitted from the AP, affecting the network’s overall coverage. References: Designing Cisco Enterprise Wireless Networks (ENWLSD 300-425)