I see 802.11h as being disabled on 2.4 GHz radio. Will this impact channel changes triggered by ChannelFly?


This article explains what is involved in 802.11h and why disabled 802.11h on 2.4 GHz radio really doesn't matter for channel changes initiated by ChannelFly.


Why the disabled 802.11h on 2.4 GHz radio doesn't matter to make clients follow the channel changes triggered by ChannelFly?

Customer Environment

Standalone AP or ZD managed wireless network

Root Cause

CSAs will be included as part of the beacons even though the 802.11h is disabled on 2.4 GHz radios.

Troubleshooting Steps

802.11h status can be seen via AP's CLI using the "get 802.11-h wlanX" command (where X represents the WLAN's ID).
By running this command you will notice that the 802.11h is enabled on 5 GHz radio while it is disabled on 2.4 GHz radios.

Since there is a belief that 802.11h support is mandatory for ChannelFly to work, this article is an attempt to clarify this a bit.

802.11h consists of two major components. One is Dynamic Frequency Selection (DFS) and the other is Transmit Power Control (TPC). This is highly applicable in avoiding interference with radars if the AP site is located near to a civil or military air facilities.

Channels Switch Announcements (CSAs) are required for ChannelFly to work and these CSAs are a small portion of 802.11h standard. Since the DFS and TPC are irrelevant for 2.4 GHz spectrum, 802.11h can stay disabled for 2.4 GHz radios. Irrespective of this, the CSA will do get sent out as part of both 2.4 GHz and 5 GHz beacons as long as ChannelFly is enabled.

So in summary, 802.11h disabled status is irrelevant to support the ChannelFly. Majority of the clients support the CSAs and follow the channel changes made by APs.

Article Number:

September 03, 2014 02:03 AM (over 6 years ago)

Configuration, Troubleshooting, Known Issues and Workarounds, ZoneDirector, ZoneFlex Indoor, ZoneFlex Outdoor


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