Users Guide

140 | Adaptive Radio Management (ARM) Dell PowerConnect ArubaOS 5.0 | [User Guide
Monitoring Your Network with ARM
When ARM is enabled, your AP will dynamically scan all 802.11 channels within its 802.11 regulatory domain at
regular intervals and will report everything it sees to the controller on each channel it scans. 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 Metrics” on page 150.)
Noise and Error Monitoring
An AP configured with ARM is aware of both 802.11 and non-802.11 noise, and will adjust to a better channel if it
reaches a configured threshold for either noise, MAC errors or PHY errors. 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.
Application Awareness
Dell APs keep a count of the number of data bytes transmitted and received by their radios to calculate the traffic
load. When a WLAN gets very busy and traffic exceeds a predefined threshold, load-aware ARM dynamically
adjusts scanning behavior to maintain uninterrupted data transfer on heavily loaded systems. ARM-enabled APs
will resume their complete monitoring scans when the traffic has dropped to normal levels. You can also define a
firewall policy that pauses ARM scanning when the AP detects critically important or latency-sensitive traffic
from a specified host or network.
ARM’s band steering feature encourages dual-band capable clients to stay on the 5GHz band on dual-band APs.
This frees up resources on the 2.4GHz band for single band clients like VoIP phones.
The ARM “Mode Aware” option is a useful feature for single radio, dual-band WLAN networks with high density
AP deployments. If there is too much AP coverage, those APs can cause interference and negatively impact your
network. Mode aware ARM can turn APs into Air Monitors if necessary, then turn those Air Monitors back into
APs when they detect gaps in coverage. Note that an Air Monitor will not turn back into an AP if it detects client
traffic (or client traffic increases), but will change to an AP only if it detects coverage holes.
ARM Profiles
You configure ARM by defining ARM profiles, a set of configuration parameters that you can apply as needed to
an AP group or to individual APs. Dell controllers have one preconfigured ARM profile, called default. Most
network administrators will find that this one default ARM profile is sufficient to manage all the Dell APs on their
WLAN. Others may want to define multiple profiles to suit their APs’ varying needs.
When managing ARM profiles, you should first consider whether or not all the APs on your WLAN operate in
similar environments and manage similar traffic loads and client types.
If your APs' environment and traffic loads are mostly the same, you can use the default ARM profile to manage all
the APs on your WLAN. If you ever modify the default profile, all APs on the WLAN will be updated with the
new settings. If, however, you have APs on your WLAN that are in different physical environments, or your APs
each manage widely varying client loads or traffic types, you should consider defining additional ARM profiles for
your AP groups. Table 33 describes different WLAN environments, and the type of ARM profiles appropriate for
each.