HPE6-A47 Designing Aruba Solutions Questions and Answers

The customer needs a solution that can terminate VPN tunnels for Aruba RAPs, which are remote access points that connect to the corporate network over the Internet. The customer has only one public IP address, which means that they need to use NAT to forward the IPsec traffic to the device that will terminate the VPN tunnel. The customer also wants N+1 redundancy, which means that they need at least two devices that can act as backup for each other in case of failure.

The solution that meets the customer requirements is to use two Aruba MCs on the same subnet that use VRRP without clustering. VRRP stands for Virtual Router Redundancy Protocol, and it is a protocol that allows multiple devices to share a virtual IP address and act as a single gateway for the network. This way, the customer can use the virtual IP address as the public IP address for the NAT, and the IPsec traffic will be forwarded to the device that is the VRRP master. If the master device fails, the backup device will take over the role of the master and continue to terminate the VPN tunnels. This provides N+1 redundancy for the customer.

The other options are not suitable for the customer requirements:

• Option B is not suitable because a Layer 3 cluster requires two public IP addresses, one for each MC. The customer only has one public IP address, so they cannot use this option.
• Option C is not suitable because VRRP does not work across different subnets. The customer needs to have the MCs on the same subnet to use VRRP.
• Option D is not suitable because a Layer 2 cluster does not support NAT. The customer needs to use NAT to forward the IPsec traffic to the MCs.

References:

• Aruba Remote Access Point (RAP) Networks Validated Reference Design)
• Aruba Mobility Controller Virtual IP Configuration Guide)
• ArubaOS 8.5 User Guide)

 The correct answer is option C, voice. Voice applications have the greatest potential impact on RF design because they are sensitive to latency, jitter, and packet loss. Voice applications also require a minimum signal strength and signal-to-noise ratio to ensure good voice quality. Therefore, an architect needs to consider the number of voice devices, the codec used, the roaming behavior, and the call admission control when planning the RF coverage for voice applications. 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 3: Wireless LAN Technologies and Standards, where the RF design considerations for voice applications are discussed. Designing Aruba Solutions Official Certification Study Guide Aruba Mobility Fundamentals Guide

 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)]

The architect should propose one LIC-MM-VA-500 license package for the customer. This license package allows the customer to deploy up to two VMMs and manage up to 500 MCs and 10,000 APs. The customer does not need any additional licenses for the MCs or the APs, as they are included in the LIC-MM-VA-500 package. The other options are either insufficient or excessive for the customer’s needs.

• Option A is insufficient because six LIC-MM-VA-50 licenses only allow the customer to manage up to 300 MCs and 6,000 APs. The customer needs to manage 300 APs and six MCs, so this option does not meet the requirement.
• Option B is excessive because one LIC-MC-VA-250 and one LIC-MC-VA-50 licenses allow the customer to deploy up to 300 MCs and 6,000 APs, which is more than what the customer needs. Moreover, one LIC-MM-VA-500 license allows the customer to deploy up to two VMMs and manage up to 500 MCs and 10,000 APs, which is also more than what the customer needs. Therefore, this option is wasteful and unnecessary.
• Option D is also excessive because one LIC-MC-VA-250 and one LIC-MC-VA-50 licenses allow the customer to deploy up to 300 MCs and 6,000 APs, which is more than whatthe customer needs. Additionally, six LIC-MM-VA-500 licenses allow the customer to deploy up to 12 VMMs and manage up to 3,000 MCs and 60,000 APs, which is way more than what the customer needs. Therefore, this option is also wasteful and unnecessary.

References:

• ArubaOS 8.5 Licensing Guide)
• Aruba Mobility Master Data Sheet)
• Aruba 7000 Series Mobility Controllers Data Sheet)

This answer is correct because it matches the scenario for which the Aruba backplane stacking technology is designed. Aruba backplane stacking technology allows up to 10 switches to be interconnected using high-speed backplane cables, creating a single logical device with a single IP address and configuration. This simplifies the management and operation of the network, as well as the redundancy design, as the stack can operate in ring or chain topology and provide fast failover in case of link or switch failure. This technology is suitable for customers who need to deploy a pair of aggregation switches in the same closet, as it reduces the number of devices and links to manage, and provides high availability and scalability for the network.

The other options are incorrect because:

• B. The customer needs to simplify the deployment of core switches which are located in different closets for redundancy purposes. This scenario is not suitable for Aruba backplane stacking technology, as it requires the switches to be physically close to each other and connected with backplane cables. A better option for this scenario would be to use Aruba Virtual Switching Framework (VSF) technology, which allows up to twoswitches to be interconnected using standard Ethernet links, creating a virtual switch that can span across different closets or racks.
• C. The customer needs to expand the network and make it possible for the current core switches to support more MAC forwarding and ARP entries. This scenario is not suitable for Aruba backplane stacking technology, as it does not increase the MAC or ARP table size of the switches. The MAC and ARP table size is determined by the hardware specifications of each switch model, and stacking them together does not change that. A better option for this scenario would be to upgrade the core switches to a higher-end model that supports more MAC and ARP entries, or to segment the network into smaller subnets to reduce the MAC and ARP traffic.
• D. The customer needs to deploy a switch at a branch office and have the switch automatically discover and join the network stack at the main office. This scenario is not suitable for Aruba backplane stacking technology, as it requires the switches to be on the same LAN and connected with backplane cables. A better option for this scenario would be to use Aruba Central, which is a cloud-based management platform that allows remote provisioning and monitoring of Aruba switches and other devices. Aruba Central can automatically discover and join the switch to the network, and apply the configuration and policies from the main office.

References:

• Aruba 2930M Switch Series - Data sheet)
• ArubaOS-Switch Virtual Switching Framework - Configuration guide)
• Aruba Central - Data sheet)

 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)

SmartLink is a technology that provides fast failover for access switches connected to the core VSF fabric. It detects link failures on the uplink ports and switches to the backup link within 50 ms. It also shuts down the primary link to prevent loops. SmartLink works with any routing protocol and does not require any additional configuration on the core switches. OSPF graceful restart is a feature that allows OSPF to continue forwarding traffic during a planned or unplanned restart of the routing process. However, it does not provide fast failover for link or device failures. BGP is a routing protocol that is mainly used for inter-domain routing and does not provide fast failover for link or device failures. VRRP is a protocol that provides redundancy for routers by creating a virtual router with a shared IP address. However, it does not provide fast failover for link or device failures. References: ArubaOS-Switch Management and Configuration Guide for WC.16.10), Aruba Validated Design: Campus Wired LAN)

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

Jitter is the variation in the delay of packets arriving at the destination. It is caused by network congestion, routing changes, or other factors that affect the transmission quality. Jitter can affect the quality of VoIP calls, as it can cause gaps, distortion, or echo in the audio. According to the Aruba Validated Reference Design for Voice and Video over Wi-Fi, the recommended maximum jitter for VoIP calls is 30 ms. Therefore, a jitter of 100 ms would typically cause a poor experience for users.

The other options are incorrect because:

• A. The packet loss is the percentage of packets that are lost or discarded during transmission. Packet loss can affect the quality of VoIP calls, as it can cause missing or corrupted audio. However, according to the Aruba Validated Reference Design for Voice and Video over Wi-Fi, the recommended maximum packet loss for VoIP calls is 1 percent. Therefore, a packet loss of 0.3 percent would not typically cause a poor experience for users.
• B. The throughput is the amount of data that can be transferred per unit of time. Throughput can affect the quality of VoIP calls, as it determines the bandwidth available for the audio. However, according to the Aruba Validated Reference Design for Voice and Video over Wi-Fi, the typical throughput for VoIP calls is 64 Kbps. Therefore, a throughput of 67 Kbps would not typically cause a poor experience for users.
• C. The latency is the delay between the sender and the receiver of packets. Latency can affect the quality of VoIP calls, as it can cause delays or out-of-sync audio. However, according to the Aruba Validated Reference Design for Voice and Video over Wi-Fi, the recommended maximum latency for VoIP calls is 150 ms. Therefore, a latency of 100 ms would not typically cause a poor experience for users.

References:

• Aruba Validated Reference Design: Voice and Video over Wi-Fi - Chapter 2)
• Aruba Certified Design Professional Official Certification Study Guide (HPE6-A47) - Chapter 7)

 A metal firewall is a significant RF obstacle that can be difficult to see visually and might require access to blueprints. A metal firewall is a type of fire-resistant barrier that is made of metal or metal-clad materials and is used to separate different sections of a building or a network. A metal firewall can block or attenuate RF signals that pass through it, causing coverage gaps, signal degradation, or interference in the wireless deployment. A metal firewall can also reflect RF signals, creating multipath fading or distortion in the wireless environment. Therefore, an architect needs to identify the location and thickness of any metal firewalls in the building and account for their impact on the RF design. A metal firewall may require additional access points, antennas, or cabling to provide adequate coverage and performance across the wireless deployment. A metal firewall may also affect the channel planning, transmit power settings, and antenna orientation of the access points and radios. A metal firewall can be difficult to see visually, as it may be hidden behind walls, ceilings, or floors, or blended with other materials.Therefore, an architect might need access to blueprints or other sources of information to locate and measure any metal firewalls in the building. References:

• RF Design | Validated Solution Guide - Aruba
• Managing and Optimizing RF Spectrum for Aruba WLANs | PDF - SlideShare
• RF Optimization - Aruba
• Advanced RF Design & Troubleshooting | PPT - SlideShare

ClearPass Access licenses are required for each unique endpoint that authenticates to ClearPass using any supported protocol, such as 802.1X, MAC authentication, web authentication, or VPN authentication1. ClearPass Onboard licenses are required for each unique endpoint that is provisioned with a certificate using the ClearPass Onboard service2. In this scenario, the customer has 900 employees and up to 30 guests a day, which means there are at most 930 users who need to authenticate to the network. Assuming each user has about two or three devices, the maximum number of devices that need Access licenses is 930 x 3 = 2790, which can be rounded up to 3000. The customer also wants to use certificates to authenticate user devices, which means they need Onboard licenses as well. However, the customer only issues laptops to the employees, which means only 900 devices need Onboard licenses. Therefore, the architect should include 3000 Access licenses and 1000 Onboard licenses in the proposal. References:

• 1: ClearPass Licensing Guide - Aruba
• 2: ClearPass Onboard Data Sheet - Aruba

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

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

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)

 Aruba Instant APs are a simple, easy to deploy, and cost-effective solution for small office buildings that need wireless access. Aruba Instant APs can form a self-organizing and self-healing mesh network that supports basic rogue AP detection and provides a stateful firewall with role-based policies. Aruba Instant APs do not require a separate controller or license, and can be managed from the cloud or a mobile app. Aruba remote APs are designed for branch or home offices that need to connect to a central controller over a WAN link. Aruba campus APs and a Virtual Mobility Controller are suitable for larger or more complex deployments that need more scalability and flexibility. Aruba campus APs and an Aruba 7005 Mobility Controller are also more expensive and require additional hardware and licensing. References: Aruba Instant Access Points), Aruba Validated Design: Campus Wireless LAN)

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))

To route at the core and extend some of the same VLANs in different buildings, the architect should recommend creating a backplane stack at the aggregation layer and a VSF fabric at the core. A backplane stack is a logical switch that combines multiple physical switches into a single unit, using dedicated stacking cables or ports. A VSF fabric is a virtual switch that combines multiple physical switches into a single unit, using standard Ethernet links. Both technologies provide high availability, scalability, and simplified management for the network12.

By creating a backplane stack at the aggregation layer, the architect can reduce the number of routing interfaces and routing protocols needed at the core layer, as well as simplify the configuration and maintenance of the aggregation switches. By creating a VSF fabric at the core layer, the architect can enable Layer 2 connectivity across different buildings, as well as provide redundancy and load balancing for the core switches. The VSF fabric can use Multi-Chassis Link Aggregation (MC-LAG) to extend the same VLANs to different aggregation stacks, without creating loops or blocking ports3.

The other options are not suitable for the customer’s requirements. Implementing broadcast filtering on switch-to-switch links across all of the buildings would not enable Layer 2 connectivity across different buildings, as it would prevent the propagation of Layer 2 control traffic, such as Spanning Tree Protocol (STP) and VLAN Trunking Protocol (VTP). Combining all switches in the aggregation layer and core into a single backplane stack would not be feasible, as it would require compatible switches and sufficient stacking ports or cables, as well as create a single point of failure for the entire network. Using VRRP on the core and aggregation switches, with the aggregation switches acting as standby, would not eliminate the routing at the aggregation layer, as it would still require the aggregation switches to participate in the routing process and maintain routing tables.

References:

• ArubaOS-Switch Stacking Guide
• ArubaOS-Switch Virtual Switching Framework Configuration Guide
• Aruba Validated Reference Design: Campus Wired LAN