2018-05-09 12:48 GMT+02:00 Seb Belcher <s.d.j.belcher@xxxxxxxxx>: > Hi all, > > I have noticed some behavior on my LEDE powered Linksys router > regarding the response to DFS 'radar detected' events when a DFS > channel has been manually selected for a 5GHz radio (i.e. non-ACS). > > hostap is correctly responding and immediately switching to a > different channel. However it then stays on this alternate channel > indefinitely. > > This causes issues when the alternate channel selected by hostapd is a > congested 5Ghz channel, resulting in poorer performance for clients. > From my understanding of the IEEE guidelines for DFS, the channel > change is only supposed to be temporary and after the DFS NOP > (non-occupancy) period has expired, which is typically 30 minutes, the > radio is permitted to switch back to the originally configured channel > if no further radar is detected for 60 seconds. > > Seemingly right now the only way to 'fix' this channel change back to > the original channel is to manually restart hostapd with the original > settings again. > You should/can write an application that will do that via hostapd_cli and chan_switch (should be able to start CAC again, if not you can easy fix it). Why application: - will monitor events from hostapd_cli monitor - why back to the same dfs channel, maybe better use another DFS? - application can check surveys and decide what channel will be the best - anyway you need also disconnect 5GHz clients because of CAC - you can start global instance of hostapd and configure/enable/disable bss via hostapd_cli So, some kind of manager would be best here - will decide what to do. > Could a feature be added to allow hostap to automatically switch back > to the configured channel after the NOP period has expired? The > trade-off here is that this action requires another 60 second DFS > scan, resulting in radio down-time, so this ideally would be > selectable in the config. > This is also possible and probably will be easy to do (conf param), but question when to do that? Wait for no-station connected? This could be one of the solutions ... BR Janusz > Thanks, > Seb > > _______________________________________________ > Hostap mailing list > Hostap@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/hostap -- Janusz Dziedzic _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
