Controller Based WLANs

What is QBSS? What information does it provides?

by on ‎07-11-2014 09:00 AM
The QBSS (QOS enhanced basic service set) information element is an 802.11e construct that enables an access point to communicate its channel usage to wireless phones. It is intended to solve the problem of candidate access point selection, or intelligent roaming. It is located in the beacon frames of access points. It can be used by QBSS-Capable devices like the Cisco 7921g. It includes three sets of information:
 
Station Count : Indicates the total number STAs currently associated with the QBSS (2 octets, unsigned integer value)
 
Channel Utilization: A percentage of time (normalized to 255) that the QAP sensed the medium was busy, Medium busy measured as physical or virtual carrier sense (CS) mechanism
 
Available Admission Capacity: Signals the remaining amount of medium time available via explicit admission control, Values from 0-31250 (2 octets long), Units of 32 µs/s
 
The reason why it was added because Cisco phones leverage that parameter and in a multivendor environment, those phones would prefer access points that have element enabled. It is much less useful in a uniform environment.
 
So if you do not have Cisco phones in a multivendor environment, do not enable it.
 
Things to Note:
 
Verify if wmm is enabled for legacy APs and WMM or High throughput  for 802.11n APs 
 
Configuration:
 
CLI
 
(Aruba) (config) #wlan ssid-profile voip
(Aruba) (SSID Profile "voip") #qbss-load-enable
(Aruba) (SSID Profile "voip") #
 
WEBUI:
 
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