Specifications

DRM - Dynamic Radio Management
Summit WM20 Technical Reference Guide, Software Version 4.296
that have selected the same channel to receive all of the other APs channel selection information. Once
the negotiation period expires, all the APs determine if they are allowed to operate on the selected
channel. The AP with the greatest need is allowed to operate on the selected channel. All other APs
return to the scanning phase.
The APs that return to the scanning phase perform a minimal scan to detect any new APs operating on
a channel. These are typically the APs that have just won the negotiation process. The channels are
evaluated once more and the best channel is selected. A new negotiation round begins for this AP.
Operation Phase
Once an AP succeeds in acquiring its selected channel, it makes a quick check of that channel to make
sure that nothing has changed during the negotiation process (i.e. a new AP appears nearby on the
channel changing the CQI or Signal Strength measurement for that channel). If everything looks ok, the
AP enables the channel and begins operation.
Channel Selection Time
The amount of time it takes to perform the first round of channel selection is approximately 60 seconds.
NOTE
This number assumes that the regulatory domain does not require radar detection. For regulatory domains requiring
radar detection, each pass though the negotiation phase requires a radar check that lasts 60 seconds. This
significantly impacts the channel selection time for the 802.11a band due to the number of available channels. In
an 802.11a environment with 19 channels and 17 APs, it can take 30 minutes to complete channel selection.
Extreme Networks is working on solutions to improve this time.
APs that lose the negotiation phase return to the scanning phase. A new scan takes approximately 15
seconds after which a new round of negotiating takes place.
The distributed nature of this algorithm results in an optimum distribution of channels over a large
number of APs. The maximum amount of time required to select channels is approximately 3 minutes.
In a large and dense deployment of APs, many groups of APs pick channels simultaneously. Each
round causes more and more APs to select appropriate channels in parallel. Even in dense deployments,
an AP will acquire the selected channel after approximately three rounds of negotiating
Management
DRM is configured and monitored centrally. The configuration of DRM consists of:
1 enable/disable DRM – global and per Access Point settings
2 group DRM configuration
3 enable/disable the avoidance of other WLANs
4 override channel assignment