Dell W-7030 AOS 6.4.x User Guide - Page 511

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 Support for 802.11n ArubaOS version 3.3.x or later supports APs with the 802.11n standard, ensuring seamless integration of 802.11n devices into your RF domain. The Dell AP's 5 Ghz band capacity simplifies the integration of new APs into your legacy network. You can also replace older APs with newer 802.11n-compliant APs while reusing your existing cabling and PoE infrastructure. A high-throughput (802.11n) AP can use a 40 MHz channel pair comprised of two adjacent 20 MHz channels available in the regulatory domain profile for your country. When ARM is configured for a dual-band AP, it will dynamically select the primary and secondary channels for these devices. It can, however, continue to scan all changes in the a+b/g bands to calculate interference and detect rogue APs. Monitoring Your Network with ARM When ARM is enabled, the Dell AP dynamically scans all 802.11 channels in its regulatory domain at regular intervals and will report everything it sees to the controller on each channel it scans. (By default, 802.11n-capable APs scan channels in all regulatory domains.) This includes, but is not limited to, data regarding WLAN coverage, interference, and intrusion detection. You can retrieve this information from the controller to get a quick health check of your WLAN deployment without having to walk around every part of a building with a network analyzer. (For additional information on the individual matrix gathered on the AP's current assigned RF channel, see ARM Coverage and Interference Metrics on page 514.) Maintaining Channel Quality Hybrid APs and Spectrum Monitors determine channel quality by measuring channel noise, non-Wi-Fi (interferer) utilization and duty-cycles, and certain types of retries. Regular APs using the ARM feature derive channel quality values by measuring the noise floor for both 802.11 and non-802.11 noise on that channel. The ARM algorithm is based on what the individual AP hears, so each AP on your WLAN can effectively "self heal" by compensating for changing scenarios like a broken antenna or blocked signals from neighboring APs. Additionally, ARM periodically collects information about neighboring APs to help each AP better adapt to its own changing environment. Configuring ARM Scanning The default ARM scanning interval is determined by the scan-interval parameter in the ARM profile. If the AP does not have any associated clients (or if most of its clients are inactive), the ARM feature will dynamically readjust this default scan interval, allowing the AP obtain better information about its RF neighborhood by scanning non-home channels more frequently. Starting with ArubaOS 6.2, if an AP attempts to scan a nonhome channel but is unsuccessful, the AP will make additional attempts to rescan that channel before skipping it and continuing on to other channels. The Over the Air Updates feature allows an AP to get information about its RF environment from its neighbors, even the AP cannot scan. If you enable this feature, when an AP on the network scans a foreign (non-home) channel, it sends an Over-the-Air (OTA) update in an 802.11 management frame that contains information about that AP's home channel, the current transmission EIRP value of the home channel, and onehop neighbors seen by that AP. Starting with ArubaOS 6.3.1, if ARM reports a high noise floor on a channel within a 40 MHz channel pair or 80 MHz channel set, ARM performs an additional 20 MHz scan on each channel within that channel pair or set, to determine the actual noise floor of each affected channel. This allows ARM to avoid assigning the overused channel, while still allowing channel assignments to the other unaffected channels in that channel pair or set. 511 | Adaptive Radio Management Dell Networking W-Series ArubaOS 6.4.x | User Guide