Changing Channel On-The-Fly

Volkan YAZICI volkan.yazici
Mon Jan 24 00:25:22 PST 2011

On Sun, 23 Jan 2011, Jouni Malinen <j at> writes:
> On Thu, Jan 20, 2011 at 04:01:20PM +0200, Volkan YAZICI wrote:
>> How can I change the channel hostapd is operating at without losing
>> established connections? Editing hostapd.conf and sending a SIGHUP makes
>> hostapd change the channel, but it loses established connections. On the
>> other hand, I don't want to edit hostapd.conf; I want to make this
>> configuration from a C/C++ application. (Hence, ioctl() calls, libnl
>> uses are welcome.) Any helps will be really appreciated.
> This is not currently supported, but will be needed for proper DFS/radar
> detection support, so there is interest in getting proper channel switch
> support added in the near future. Since hostapd is in control of the
> Beacon frame template with some drivers, it needs to know the current
> channel and direct ioctl/libnl use is not a viable direction for this in
> many cases.

So you say that "changing the channel ap is operating at on-the-fly
without losing established connections" is supported by 802.11gn, but
this feature is not yet provided by hostapd, right?

If we would forget the "without losing established connections" phrase,
is it still not possible to change the channel even via wpa_ctrl
interface? Is SIGHUP'ing hostapd my only choice? Considering this[1]
hostapd+iwconfig anomaly, how can I learn the current channel? Does
wpa_ctrl provide that information?



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