Mod09MBC-ARM-6.3-v1.3

Aruba Bootcamp – Adaptive Radio Management

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CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved

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Aruba's Adaptive Radio Management (ARM) technology maximizes WLAN performance even in the highest traffic networks by dynamically and intelligently choosing the best 802.11 channel and transmit power for each Aruba AP in its current RF environment.


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Aruba’s ARM technology solves wireless networking challenges such as large deployments, dense deployments, and installations that must support VoIP or mobile users. Deployments with dozens of users per access point can cause network contention and interference, but ARM dynamically monitors and adjusts the network to ensure that all users are allowed ready access. ARM provides the best voice call quality with voice-aware spectrum scanning and call admission control. Static site surveys can help you choose channel and power assignments for APs, but these surveys are often time-consuming and expensive, and only reflect the state of the network at a single point in time. ARM is more efficient than static calibration, and, unlike older technologies, it continually monitors and adjusts radio resources to provide optimal network performance.


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Aruba Bootcamp – Adaptive Radio Management Automatic power control can adjust AP power settings if adjacent APs are added, removed, or moved to a new location within the network, minimizing interference with other WLAN networks. ARM adjusts only the affected APs, so the entire network does not require systemic changes. ARM is a distributed approach to enable self-configuring, self-healing wireless networks that make use of the frequency bands allowed in a given regulatory domain. In order to fully utilize the available spectrum allocated in the ISM and UNII bands in 2.4 GHz and 5 GHz and thereby increase the system capacity and number of users supported, it is important to carefully reuse the frequencies over the area of coverage. The traditional approach to handle this is careful RF planning of static frequency and power settings prior to the deployment to determine the placement and channel provisioning for the different APs. But as AP deployments grow denser and larger-scale in order to improve capacity and coverage, static pre-deployment calibrations may prove inadequate and time-consuming. It is important for the wireless system to adapt to dynamic events including interference, noise, packet error rates, etc. - in order to fully utilize the raw capacity provided by the underlying PHY layer.

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In the past, an extensive and time consuming static site survey was needed for deciding how many APs were needed, where to physically place the APs, what 802.11 channels should be set for each AP, and what Tx-power should be set for each AP in order to provide the most optimal WLAN environment. Today, Aruba RF Plan or Visual RF is used to calculate the number of APs needed and dynamically place them on a virtual floor plan. After physical AP installation is complete, the Aruba APs will connect to the Aruba Controller and then ARM will dynamically find the best performing 802.11 channel and transmit power based on their current environment. ARM, when enabled, is a continuous process. It allows the system to detect changes in the RF and to dynamically react to maintain the most optimized RF system possible.


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When deploying APs, they will use default power and channel values as shown on the slide. Left in this condition, the system would not be very functional.


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After ARM, the APs change channel assignments and modify power levels to provide a nonoverlapping system. Although this image shows “white areas” without coverage, that is not really the case. The heat plans display coverage at specific transmission rates. You can change the rate to display on the heat plan. The highest rates will not have as much coverage as lower data rates.


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Too many decisions are left to the client Clients lack a system-level perspective with which to make intelligent decisions Client connects to closest AP which may not be optimal in dense deployments Shared media nature of Wi-Fi Bandwidth and channels are limited and must be shared – clients are not optimized for this purpose Client with more optimized TCP stacks will starve other clients

Multiple Wi-Fi client technologies in use Protection mechanisms and interoperability algorithms cause new clients to slow in the presence of old ones 802.11b clients will slow down 802.11g/n, 802.11g will slow down 802.11n Clients Result: unpredictable/unreliable wireless connectivity


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Band steering reduces co-channel interference and increases available bandwidth for dual-band clients, because there are more channels on the 5GHz band than on the 2.4GHz band. Dual-band 802.11n-capable clients may see even greater bandwidth improvements, because the band steering feature will automatically select between 40MHz or 20MHz channels in 802.11n networks This feature is disabled by default, and must be enabled in a Virtual AP profile. The band steering feature supports both campus APs and remote APs that have a virtual AP profile set to tunnel, split-tunnel or bridge forwarding mode


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The spectrum load balancing feature helps optimize network resources by balancing clients across channels, regardless of whether the AP or the controller is responding to the wireless clients' probe requests. The controller uses the ARM neighbor update messages that pass between APs and the controller to determine the distribution of clients connected to each AP's immediate (one-hop) neighbors. This feature also takes into account the number of APs visible to the clients in the RF neighborhood and can factor the client’s perspective on the network into its coverage calculations. Spectrum load balancing is disabled by default, and is enabled for 2.4G traffic through an 802.11g profile or for 5G traffic through an 802.11a RF management profile If the client receiving the error code 17 tries to associate to the AP a second time, it will be admitted. If a client is rejected by two APs in a row, it will be admitted by any AP on its third try. Note that the spectrum load balancing feature only affects the association of new clients; this feature does not reject or attempt to balance clients that are already associated to the AP.


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With a fixed time period the controller looks at all the clients for a VAP. This applies to downstream traffic only . ARM can be configured such that it does:

1. Implements a fairness set of process for all clients. Basically for a certain amount of time ARM will divide the time up equally amongst clients no matter what their rate or how far or close they are to the AP. Each client gets “tokens” that represent this time slice. Note in some cases clients do not use the tokens at all because they do not receive anything during the time slice. 2. Implements a weighted fairness process where it still slices the time and gives time in token increments, however more tokens are given for 802.11a than 802.11b . More tokens are given for 802.11n than for for 802.11a. i.e Faster capable clients will get more time allocated to them. If the ARM buffers reach internal threshold levels ARM can participate in TCP windowing and throttle the sender and/or drop low priority UDP packets but it will always forward without delay Voice and Multicast.


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Enable Mode Aware in ARM profile for this feature to take effect

Designed for high-dense AP deployments, in order to maintain 802.11 channel performance even in the presence of excessive co-channel interference Optimizes AP density depending on user density.

In high-user density conditions, all APs service clients, providing highest capacity. In low user-density conditions, some non-edge APs automatically switch to AM mode. This minimizes unnecessary roaming and co-channel interference while allowing expansion in capacity when required.This is decided by the acceptable coverage index This is decided based on how strongly each AP sees other valid APs on that channel.


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802.11 clients tend to associate to an AP and then remain associated even when they move closer to another AP with better signal strength or a higher data rate. This is referred to as stickiness. Client Match solves the problem of sticky clients by steering clients to associate to APs with better 802.11 signal quality. If you are talking on your cell phone while driving down the road, you are probably going through several different cell towers. As you pass the towers, your active call and your devices is being actively steered by the cell company to the best cell tower for your device. Similarly, ClientMatch enables the infrastructure to steer the devices to the best possible AP based on several different factors like device type, location of the device, signal to noise ratio in the vicinity of the device as well the load on the Access Point. You can see this in action on the animated slide here where the iPad is being steered to another AP. With ClientMatch, the goal is to improve the quality of every single connection which effectively boosts overall network performance providing users with a superior user experience.


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When it comes to performance, there is no match to Aruba’s ClientMatch technology.. The fundamental issue that on a Wi-Fi network the client device is in control. They make their own decisions on which AP to connect to, how long to stay connected to that AP and when to let go leading to the well known sticky client problem. Problem with this approach is that the Client devices have a narrow view of the network and are generally making decisions that may not be in the best interests of the overall network. ClientMatch fixes this by enabling the Wi-Fi infrastructure to make decisions on behalf of the client while keep a global network wide view in mind. As you see on this slide, Aruba has already been granted a patent on this technology making it unique and highly differentiated. Without ClientMatch, an 802.11ac network will operate no different than a 802.11n network and users will not experience much performance gains. In a real world test, we observed 98% of the devices significant improvement in their Signal to noise ratio when ClientMatch was enabled on the network.


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Layer 1 Client match ensures clients associate to an AP with the best reception.


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Layer 2 and 3 client match ensures the highest possible throughput for each client’s data.


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Why upgrade to 802.11ac if you cannot use the 802.11ac data rates?


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AirWave provides visibility to the IT admins to get an understanding of their ongoing Wi-Fi performance With ClientMatch, now every device on the network can be assigned a health metric associated with it. As you can see on the screenshot here, we have a lot of green devices but a red and orange one too which don’t seem to be in the best of health. Airwave makes it easier for admins to monitor and troubleshoot these clients with a lower health metric. In addition, you can also see which client was steered by ClientMatch, why it was steered and when. With this level of data, troubleshooting user complaints is much more easy and intuitive


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It is decided by the acceptable coverage index that if there is more than acceptable coverage index worth of coverage on the channel and all channels on that band have enough coverage, then the AP will convert to an AM to reduce co-channel interference. This is decided based on how strongly each AP sees other valid APs on that channel. Distributed : No more than 5 channels are changed at any one time.


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*The scan interval can be adjusted to less than 10 seconds. However, this comes at the cost of going off channel too often. It can affect existing AP clients.


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The interference index is a summary of all SNR’s heard by the AP that’s being analyzed and its RF neighborhood. The coverage index is a weighted figure. Choosing the channel with the least Interference index

The channel that ARM switches to must have a “minimum index value” (configurable) ARM chooses a channel closest to an “ideal index value” (configurable) A dampening factor prevents flapping


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This is an example of how ARM optimizes channels

In the 1st figure the AP’s are allocated channels based on the default value, and ARM scanning is disabled The 2nd figure shows the channel allocation based on ARM readings after ARM scanning is enabled


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This command shows the changes made by ARM, here you can see the changes in the power setting of a AP EDSrvAP1 , the channel changes can also be seen with this command


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Scanning – ARM scanning, enabled by default Do not disable Scanning unless you want to disable ARM and manually configure AP channel and transmission power Client Aware -if enabled the AP does not change channels if there is an active client associated to that AP, enabled by default Rogue AP Aware - if enabled Aruba APs may change channels to contain off-channel rogue APs with active clients, disabled by default Power Save Aware Scan - if enabled the AP will not scan a different channel if it has one or more clients that is in power save mode, enabled by default Voip Aware Scan - if enabled the AP will not attempt to scan a different channel if one of its clients has an active VoIP call, enabled by default Video Aware Scan - if enabled the AP will not scan if video session is in progress, enabled by default Mode Aware Arm - if enabled, Arm will turn AP to Air Monitor to avoid high interference, disabled by default . Mode aware ARM turns Air Monitors back into APs when they detect gaps in coverage


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Spectrum analysis identifies interference and its sources

There is no substitute for real-time analysis at the point-of-problem Best integrated into the WLAN infrastructure

Hand-held tools are useful only when IT staff are on-site and interference is present – an unlikely combination in distributed enterprises FFT (Fast Fourier Transform) displays, spectrograms, interference classification Interference charts, channel quality and availability metrics, recording playback for extended unattended data capture


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In order to convert an AP to a spectrum monitor you must have an AP license and an RF protect license for each AP on that controller.


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A spectrum analysis client can simultaneously access data from up to four individual spectrum monitor radios. Each spectrum monitor radio, however, can only be connected to a single client WebUI When you select a specific spectrum monitor to stream data to your client, the controller first checks the availability the spectrum monitor, to verify that it is not subscribed to some other client. Once the spectrum monitor has been verified as available, the spectrum monitor establishes a connection to the client and begins sending spectrum analysis data either every second or every five seconds, depending on the type of data being requested When you disconnect a spectrum monitor from your client, the AP will continue to operate as a spectrum monitor until you return it to AP mode A spectrum monitor will automatically disconnect from a client when you close the browser window you used to connect the spectrum monitor to your client


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Any APs placed in a AP group where the mode is set to Spectrum will only operate as spectrum monitors All APs in the group that support the spectrum monitoring feature start to function as hybrid APs Hybrid APs display data for their one monitored channel only. This also limits the number of graphs that can be used. Hybrid mode is not supported on legacy APs nor the 120 series of APs You can override any APs in the network to functions as a spectrum monitor using the Spectrum Local Override


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Each controller can support up to 20 spectrum monitor radios

When converting a group of APs to spectrum monitors using their 802.11a/802.11g radio profiles, all APs in the group will stop serving clients and will act as spectrum monitors only. Therefore, before you convert an entire group of APs to spectrum monitors, be sure that none of the APs are currently serving clients, as that may temporarily interrupt service to those clients


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The spectrum local override profile allows the spectrum monitor to continue to inherit all other settings from its 802.11a/802.11g radio profiles. When the spectrum local override is removed, the AP automatically reverts to its previous mode as defined it its 802.11a or 802.11g radio profile settings. If you use the local override profile to change an AP radio to a spectrum monitor, you must do so by accessing the WebUI or CLI of the controller that terminates the AP


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Each 802.11a and 802.11g radio profile references a spectrum profile

Profile defines the default ageout times for each monitored device type

Spectrum Band - Select the spectrum band you want the radio to monitor. 2GHz (channels 1-14)

5GHz-lower (channels 36-64) 5GHz-middle (channels 100-140) 5GHz-upper (channels 149-165). This is the default setting for the 5Ghz spectrum.


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You can view classification, device and channel information for any active spectrum monitor via the controller's command-line interface, regardless of whether or not that spectrum monitor is sending real-time spectrum data to another client WebUI


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Monitoring -> Spectrum Analysis It opens a new pop up window

If you have no SM connected to your Spectrum UI, the Spectrum Dashboard screen will show the screen above which says click here to connect to at least one Spectrum Monitor That takes you to Spectrum Monitor screen where you can add SM to you dashboard. If you want to add more SM to your dashboard you can directly go to Spectrum Monitor tab on the pop window.


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Once you have connected one or more spectrum monitors to your Spectrum Analysis client, the Monitoring>Spectrum Analysis>Spectrum Monitors window displays a table of currently connected spectrum monitors. This table includes the name of each spectrum monitor, its current radio band (2GHz or 5GHz)Here you see a SM already connected to this dashboard You can click on disconnect to free up a SM for any other Spectrum client to view Spectrum Analysis information from that particular SM Beginning in AOS 6.2 you no longer need to select 5GHz lower / mid / upper bands. Now, when viewing the Real-Time FFT chart you select which band to display within the chart.


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To identify the spectrum monitor radio whose data you want to appear in the Spectrum Analysis dashboard In the graph title bar, click the down arrow by the Please select a spectrum monitor heading A drop-down list appears with the name of all spectrum monitor radios currently connected to the client Select a spectrum monitor from the list. The spectrum monitor name will appear in the chart title bar and the chart will start displaying data for that spectrum monitor


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To replace an existing graph with any other type of graph or chart:

Click the down arrow at the far right end of the graph title bar to display a drop-down menu of chart options. Click Replace With to display a list of available graphs Click the name of the new graph you want to display


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In built help menu gives descriptions of the various chart and graph views available in Spectrum Dashboard To access the Spectrum Help Menu click on the “ ? “ symbol at the top right corner of the dashboard


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The spectrum analysis tool allows you to record up to 60 continuous minutes (or up to 10 Mb) of spectrum analysis data. By default, each spectrum analysis recording displays data for the RealTime FFT, FFT Duty Cycle, and Swept Spectrogram charts While the recording is in progress, a round, red recording icon and recording status information appears at the top of the spectrum dashboard. You will be allowed to view data for other spectrum monitors and charts while the recording is in progress If you want to stop the recording before recording period has finished, click the Stop button by the recording status information. When you click the stop button, a popup window appears and allows you to stop and delete the current recording, stop and save the recording in its current state (before it has completed), or continue recording again. Configurable recording settings allow you to start a recording session immediately, or schedule a recording time to begin at a later date and time


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Once you have saved a spectrum analysis recording, you can play it back at any time. The spectrum monitor does not have to be subscribed to your spectrum analysis client in order to play back a recording from that spectrum monitor radio. Note, however, that you cannot play back an existing recording while another recording session is currently in progress


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Mod09MBC-ARM-6.3-v1.3

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