HPE6-A47 Designing Aruba Solutions Question and Answers

The Aruba 2930F Switch Series is a stackable Layer 3 switch series that provides performance and ease of use for enterprises, small and medium-sized businesses, and branch office networks1. It comes with an enterprise-grade feature set that includes static and RIP routing, IPv6, ACLs, robust security, and QoS1. The 2930F Series supports more options for class-based Quality of Service (QoS) policies than the 2540 Series2. This feature is crucial for a customer who needs a wired network solution that can recognize and prioritize a wide array of different types of traffic, including casual Web browsing, voice, video, SAP Online, and file sharing.

References:

• HPE Aruba Networking 2930F Switch Series
• Why would the architect choose the 2930F rather than the 2540 Switch Series for this customer?

The customer wants to use certificates to authenticate user devices, which means that they need a strong and secure method of verifying the identity of the devices that connect to the employee WLAN. The best option for this is to use EAP-TLS instead of PEAP-MSCHAPv2. EAP-TLS stands for Extensible Authentication Protocol-Transport Layer Security, and it is a protocol that uses certificates on both the client and the server side to establish a mutual authentication and a secure channel for data exchange. EAP-TLS is considered the most secure EAP method, as it prevents common attacks such as dictionary attacks, man-in-the-middle attacks, and replay attacks.

The other options are not suitable for the customer requirements:

• Option B is incorrect because TKIP encryption is weaker than AES encryption. TKIP stands for Temporal Key Integrity Protocol, and it is an older encryption method that was designed to replace WEP, which had serious security flaws. However, TKIP also has some vulnerabilities, and it is not recommended for modern WLANs. AES stands for Advanced Encryption Standard, and it is a newer and stronger encryption method that provides better security and performance for WLANs.
• Option C is incorrect because WPA2-PSK is less secure than WPA2-Enterprise. WPA2-PSK stands for Wi-Fi Protected Access 2-Pre-Shared Key, and it is a security mode that uses a common passphrase or key to authenticate all devices that connect to the WLAN. However, this passphrase or key can be easily compromised or shared, and it does not provide individual authentication or encryption for each device. WPA2-Enterprise stands for Wi-Fi Protected Access 2-Enterprise, and it is a security mode that uses a RADIUS server to authenticate each device individually and dynamically generate encryption keys for each session. WPA2-Enterprise provides better security and scalability for WLANs.
• Option D is incorrect because TTLS does not use certificates to authenticate user devices. TTLS stands for Tunneled Transport Layer Security, and it is a protocol that uses certificates only on the server side to establish a secure tunnel for data exchange. The client side can use different methods to authenticate, such as passwords, tokens, or certificates. However, TTLS does not require certificates on the client side, and it is less secure than EAP-TLS.

References:

• ArubaOS 8.5 User Guide)
• ArubaOS 8.5 Security Guide)
• Aruba Certified Design Professional Official Certification Study Guide (HPE6-A47))

DSCP (Differentiated Services Code Point) is a method of marking network packets with different priorities based on the type of traffic they carry. DSCP values range from 0 to 63, with higher values indicating higher priority. DSCP values are typically mapped to one of the four WMM (Wi-Fi Multimedia) queues, which are used to prioritize wireless traffic on the access points and controllers. WMM queues are: voice, video, best effort, and background12.

The default QoS settings for Aruba APs and controllers map the DSCP values to the WMM queues as follows3:

Table

DSCP Value

WMM Queue

0-7

Background

8-23

Best Effort

24-39

Video

40-63

Voice

According to these settings, the DSCP values 46 and 34, which are assigned to voice and video traffic by Windows policies, will both be mapped to the video WMM queue. This means that both types of traffic will receive the same priority, and voice traffic will not receive the highest priority that it should. This can result in poor voice quality, increased latency, jitter, or packet loss, especially when the network is congested or bandwidth is limited. Voice traffic is more sensitive to these factors than video traffic, and requires strict QoS to ensure optimal performance and user experience4.

To avoid this potential issue, the architect should explain to the customer that they need to modify the QoS settings on the Aruba APs and controllers to match the DSCP values assigned by Windows policies. This can be done by using the following commands on the Aruba controller3:

(config) #wmm traffic-management-profile voice

(config) #dscp 46

(config) #wmm traffic-management-profile video

(config) #dscp 34

These commands will map the DSCP value 46 to the voice WMM queue, and the DSCP value 34 to the video WMM queue, ensuring that voice traffic receives the highest priority and video traffic receives the second highest priority. This will improve the QoS for the Skype for Business UC solution and enhance the end-user experience.

References:

• 1: https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/1-overview/qos.htm
• 2: https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/1-overview/wmm.htm
• 3: https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/1-overview/qos-mapping.htm
• 4: https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/1-overview/qos-voice.htm

 References:https://www.arubanetworks.com/assets/ds/DS_7200Series.pdf

• Aruba Mobility Controller Data Sheet (Aruba Networks)
• Designing Aruba Solutions Study Guide (HPE Press)

This is the general recommendation from the AirWave Server Sizing Guide1, which provides guidelines for selecting and configuring hardware based on the number of devices, clients, and features. The guide also lists the conditions that impact hardware sizing, such as polling frequency, RAPIDS, VisualRF, and Clarity.

References: 1: AirWave 8.2.14.0 Server Sizing Guide - Aruba, page 5.

Deployed as a purpose-built hardware or virtual machine image, each AirWave server supports up to 4,000 network devices (access points, switches, and controllers).https://www.arubanetworks.com/assets/ds/DS_AW.pdf

ClearPass OnConnect is a feature of the ClearPass Policy Manager that allows wired authentication on switches that do not support 802.1X or RADIUS protocols. ClearPass OnConnect uses SNMP to monitor and control the switch ports based on the device profiles and policies defined in ClearPass12. ClearPass OnConnect can provide the following benefits for the customer:

• It can enable wired authentication without requiring any changes to the existing switch infrastructure or the end-user devices. This can save the customer’s budget and time, as well as minimize the network disruption and user impact.
• It can provide visibility and control over the wired devices, such as printers, IoT devices, and laptops, that connect to the network. ClearPass OnConnect can identify the device type, user role, and location, and apply the appropriate access policies based on the customer’s security and compliance requirements. For example, ClearPass OnConnect can allow only authorized devices and users to access certain network resources, or quarantine or block any unknown or non-compliant devices.
• It can integrate with the other components of the Aruba solution, such as the MCs, MMs, APs, AirWave, and ClearPass Guest, to provide a consistent and unified network management and security solution across the wired and wireless networks. For example, ClearPass OnConnect can leverage the device profiles and policies from ClearPass Guest, or share the network health and performance data with AirWave.

Therefore, by explaining this feature, the architect can justify the proposed solution and show how it can meet the customer’s needs and expectations for wired authentication, as well as wireless authentication.

References:

• 1: https://www.arubanetworks.com/techdocs/ClearPass/6.7/PolicyManager/index.htm#CPPM_UserGuide/Admin/OnConnect.htm
• 2: https://www.arubanetworks.com/assets/tg/TB_ClearPass_OnConnect.pdf

The Aruba MC 7010 and 7024 are both designed for small to mid-sized campuses and branches, but they have some differences in their features and specifications. One of the main differences is the number and type of ports they offer. The MC 7010 has 16 10/100/1000BASE-T ports, while the MC 7024 has 8 10/100/1000BASE-T ports and 8 1000BASE-X SFP ports1. This means that the MC 7024 can support more APs that require fiber connections, such as the AP-387 or the AP-5352. The MC 7024 also supports 10G ports, which can provide higher bandwidth and performance for the network backbone3.

Therefore, if the customer needs to connect 20 APs directly to the MC, and some of them require fiber or 10G connections, the MC 7024 is a better choice than the MC 7010. The other options (A, B, and C) are not relevant for choosing between the MC 7010 and 7024, as both models can support up to 64 APs and 4096 users or devices, and both models can provide PoE+ on 12 ports1.

References:

• Aruba 7000 Series Mobility Controllers Data Sheet
• Aruba Access Points Data Sheet
• Aruba 7000 Series Mobility Controllers and Gateways

 Aruba AirWare is a network management solution that provides real time statistics and assessment of call quality for Skype for Business UC solution. It integrates with Skype for Business SDN API to monitor and troubleshoot voice and video calls, and optimize network performance and user experience. It also provides visibility into network health, application performance, and user behavior across wired and wireless networks. Aruba Central is a cloud-based network management solution that does not support Skype for Business integration. Aruba Mobility Master (MM) is a network controller that manages Aruba access points and switches, but does not provide call quality statistics or assessment. Aruba ClearPass is a network access control solution that provides secure authentication and policy enforcement, but does not monitor or optimize Skype for Business calls. References: Aruba AirWave Network Management), Aruba AirWave and Microsoft Skype for Business Integration Guide)

 In local mode, the IAP cluster at the branch office has a local subnet and the master IAP of the cluster acts as the DHCP server and gateway for clients. The local mode provides access to the corporate network using the inner IP of the IPsec tunnel. The local mode is recommended for this scenario because it allows the branch office to remain functional even if the link to the main office fails, as the clients can still obtain IP addresses and access local resources. The local mode also avoids the need for additional routing or switching configuration on the MC or the branch office network12. References:

• 1: Understanding IAP-VPN Architecture - Aruba
• 2: IAP-VPN Forwarding Modes - Aruba

An active site survey is a method of measuring and validating the wireless coverage, capacity, and performance of a network in a specific environment. It involves deploying temporary APs in the proposed locations, collecting data using a survey tool, and analyzing the results to optimize the network design. A heat map is a graphical representation of the wireless signal strength, interference, noise, or other metrics in different areas of the site. A heat map with proposed AP locations and actual tested coverage is a deliverable that shows the customer the expected performance of the new 802.11ac-based solution, and allows the architect to fine-tune the AP placement, channel selection, transmit power, and antenna orientation. This deliverable also helps the customer to verify that the network meets their requirements for coverage, capacity, and quality of service. References:

• Aruba Certified Design Professional Official Certification Study Guide (HPE6-A47) - Chapter 5)
• Aruba Validated Reference Design: Wireless LAN Site Surveys - Chapter 3)
• Aruba Validated Reference Design: 802.11ac Networks - Chapter 4)

 The number of devices used by each user is an important factor for creating the RF plan, as it affects the network capacity, bandwidth demand, and interference level. The architect should estimate the average number of devices per user and the types of applications they use, such as voice, video, or data. This will help the architect to determine the optimal number and placement of access points, the channel width and selection, the transmit power and data rates, and the radio resource management settings.

The OS used on wireless devices, whether BLE wayfinding is required, and the software version on MCs are not directly relevant for creating the RF plan, as they do not affectthe physical layer characteristics of the wireless network. However, they may have implications for other aspects of the network design, such as security, compatibility, and features.

References:

• RF Design | Validated Solution Guide - Aruba
• Enterprise Mobility 8.5 Design Guide - WLAN RF Design Considerations [Cisco 5500 Series Wireless Controllers] - Cisco

The customer needs to upgrade their wireless network, which has a single large building with four floors. The customer requires 30 APs on each floor, totaling 120 APs for the whole building. The customer also wants to use a MM-based architecture, and deployone Aruba 7030 MC on each floor, with the MCs combined in a cluster for seamless client failover and roaming. However, the proposed solution does not meet the customer’s requirements, because the Aruba 7030 MC does not support enough APs for the customer’s needs. Each Aruba 7030 MC can only support up to 64 APs, which means that deploying one on each floor would not be enough to support all the required APs. The architect should explain this limitation to the customer, and suggest a different solution that can support more APs, such as using a higher-capacity MC model, or deploying more MCs per floor.

References:

• Aruba 7000 Series Mobility Controllers Data Sheet)
• ArubaOS 8.5 User Guide)
• Aruba Certified Design Professional Official Certification Study Guide (HPE6-A47))

 A collision domain is a logical area of the network where devices share the same wireless medium and may interfere with each other’s transmissions. In a WLAN, a collision domain is defined by the channel and the coverage area of an AP or a client. Devices that operate on the same channel and are within range of each other belong to the same collision domain and must contend for access to the medium using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Devices that operate on different channels or are out of range of each other belong to different collision domains and do not interfere with each other.

In this scenario, the architect plans 12 APs for an auditorium that is 325 square meters (3,498 square feet). Each AP has one 2.4 GHz radio and one 5 GHz radio. Both types of radios use 20 MHz channels. Assuming that DFS channels can be used in this design, the question is how many 5 GHz collision domains does this design provide.

To answer this question, we need to consider the following factors:

• The number of available 5 GHz channels in the regulatory domain of the auditorium. Different countries have different regulations on the use of the 5 GHz band, which affects the number and availability of channels for WLANs. For example, in the United States, there are 25 non-overlapping 20 MHz channels in the 5 GHz band, but some of them are subject to Dynamic Frequency Selection (DFS) requirements, which means that they must avoid interfering with radar systems by detecting and switching to another channel if radar signals are present. In other countries, such as Japan, there are 19 non-overlapping 20 MHz channels in the 5 GHz band, but some of them are restricted to indoor use only. Therefore, the number of available 5 GHz channels for the design depends on the regulatory domain of the auditorium.
• The channel assignment and distribution of the 12 APs in the auditorium. The channel assignment and distribution of the APs affect the number and size of the collision domains in the WLAN. Ideally, the APs should be assigned to non-overlapping channels and distributed evenly across the auditorium to provide optimal coverage and capacity, while minimizing co-channelinterference and adjacent channel interference. Co-channel interference occurs when devices on the same channel interfere with each other, while adjacent channel interference occurs when devices on nearby channels interfere with each other. Both types of interference degrade the performance and quality of the WLAN. Therefore, the channel assignment and distribution of the APs should follow the best practices of RF design, such as using a channel reuse plan, avoiding channel overlap, and adjusting the transmit power and antenna gain of the APs to match the coverage and capacity requirements of the auditorium.
• The coverage and capacity requirements of the auditorium. The coverage and capacity requirements of the auditorium affect the number and placement of the APs and the transmit power and antenna gain settings of the radios. The coverage requirement refers to the minimum signal strength and signal-to-noise ratio (SNR) that the APs and clients need to maintain a reliable wireless connection. The capacity requirement refers to the maximum number of clients and the minimum throughput and quality of service (QoS) that the APs and clients need to support the applications and services of the auditorium. The coverage and capacity requirements of the auditorium depend on the size and shape of the space, the density and distribution of the clients, the types and characteristics of the applications and services, and the performance and capabilities of the devices. Therefore, the coverage and capacity requirements of the auditorium should be determined by conducting a site survey and a network analysis, and then used to guide the design and configuration of the APs and radios.

Based on these factors, we can estimate the number of 5 GHz collision domains in the design as follows:

• Assuming that the auditorium is located in the United States and that DFS channels can be used in the design, there are 25 non-overlapping 20 MHz channels in the 5 GHz band. However, not all of them may be available or suitable for the design, depending on the presence and activity of radar systems in the area, the compatibility and support of the APs and clients, and the interference and noise level of the environment. Therefore, we will use a conservative estimate of 15 available 20 MHz channels in the 5 GHz band for the design.
• Assuming that the 12 APs are assigned to non-overlapping channels and distributed evenly across the auditorium, each AP will have its own 5 GHz collision domain, as there will be no co-channel interference or adjacent channel interference among the APs. Therefore, there will be 12 5 GHz collision domains in the design, corresponding to the 12 APs.
• Assuming that the coverage and capacity requirements of the auditorium are moderate and that the transmit power and antenna gain settings of the radios are adjusted accordingly, each AP will cover an area of about 27 square meters (290 square feet), which is roughly the size of a small classroom. This means that the APs will provide adequate signal strength and SNR for the clients, while avoiding excessive overlap and interference among the APs. Therefore, there will be no need to further divide or merge the 5 GHz collision domains in the design, as they will match the coverage and capacity requirements of the auditorium.

Hence, the number of 5 GHz collision domains in the design is 12, which is the answer option C. References:

• RF Design | Validated Solution Guide - Aruba
• Configuring 2.4 Ghz and 5 Ghz Radios - Aruba
• Chapter T-5: Understanding RF Collision Domains - Aruba
• [Aruba Certified Design Professional Official Certification Study Guide (HPE6-A47)]

whether the MC needs to support advanced 8.x features. This is because the Aruba 7000 Series MCs are based on the older hardware platform and can only run up to ArubaOS 6.5.x, while the Aruba 7200 Series MCs are based on the newer hardware platform and can run ArubaOS 8.x and above. ArubaOS 8.x introduces many advanced features, such as clustering, MultiZone, AirMatch, and dynamic segmentation, that are not supported by the Aruba 7000 Series MCs. Therefore, if the architect needs to design a solution that leverages these features, the Aruba 7200 Series MCs are the better choice.

Option A is incorrect because the number of wireless devices that the MC needs to support is not a key criteria to choose between the Aruba 7000 Series or 7200 Series MCs.Both series can support a similar number of devices, depending on the model and license.

Option B is incorrect because whether the MC needs to terminate VPN tunnels is not a key criteria to choose between the Aruba 7000 Series or 7200 Series MCs. Both series can terminate VPN tunnels, such as IPSec, GRE, and RAP, depending on the model and license.

Option C is incorrect because the need to deploy controllers in a cluster is not a key criteria to choose between the Aruba 7000 Series or 7200 Series MCs. Both series can participate in a cluster, as long as they run the same ArubaOS version and have the same license.

References: The information can be referenced from the official HPE documents and learning materials available on HPE Press and Aruba Networks. Specifically, it aligns with the objectives outlined in Chapter 6: Wireless Network Design, where the MC selection and ArubaOS 8.x features are discussed. Designing Aruba Solutions Official Certification Study Guide Aruba Mobility Controller Data Sheet ArubaOS 8.7 User Guide

 To ensure that wireless voice traffic is properly prioritized for Microsoft Skype for Business, the architect should set up firewall policies and SDN to mark voice on the MCs or MM. Firewall policies are used to classify and prioritize traffic based on the application, user role, device type, and location. SDN is used to integrate with the Skype for Business SDN API, which provides real-time information about voice and video sessions, such as source and destination IP addresses, ports, codecs, and quality metrics. By using firewall policies and SDN, the MCs or MM can dynamically mark voice traffic with the appropriate DSCP values and queue them in the highest priority queue on the wireless and wired network12.

The other options are not sufficient or relevant for ensuring wireless voice traffic prioritization for Skype for Business. Broadcast suppression combined with AirGroup is used to reduce the network overhead and improve the user experience for wireless devices that use multicast or broadcast protocols, such as Apple Bonjour or Microsoft UPnP3. Airtime Fairness set to fair-access is used to balance the airtime usage among clients with different capabilities and data rates, such as 802.11ac and 802.11n4. Voice-aware Layer 3 roaming is used to enable seamless handoff of voice sessions across different subnets without dropping the call5. While these features may enhance the overall wireless performance and reliability, they do not directly prioritize voice traffic for Skype for Business.

References:

• Aruba Validated Reference Design: 802.11ac Networks
• Aruba Validated Reference Design: Skype for Business
• Aruba Validated Reference Design: AirGroup
• Aruba Validated Reference Design: Adaptive Radio Management
• Aruba Validated Reference Design: Voice over Wireless LAN

In the event of an MM outage, MCs continue to use their existing licenses for 30 days, and the network remains up. However, you cannot change the configuration items in the controller network. In addition, the MM manages many of the higher level functions that can cause issues in the network if the MM fails. Aruba recommends a backup MM for these situations. From an economic point of view, a backup MM for a VMM is free. If a customer has a hardware MM, the customer must purchase a backup hardware MM.

https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/vrrp/conf-stby-mm-l3red.htm