ap scanning?

Johannes Berg johannes
Wed May 4 01:50:03 PDT 2011

On Tue, 2011-05-03 at 16:57 -0700, Daniel Halperin wrote:

> > I don't think hostapd scans, but how are you connecting the client? It
> > could be scanning.
> The problem is hard to reproduce, but appears to happen ~30s after
> something I do, such as associating or connecting the card or starting
> a TCP session, (usually between seconds 25-27 of the iperf transfer).
> Both endpoints are running Ubuntu 10.04.2 LTS, and I've uninstalled
> from both Network-Manager, which is the typical source of these woes.
> The AP is set up as follows:
> rmmod iwlagn cfg80211 mac80211
> modprobe iwlagn debug=0x40000
> sudo ifconfig wlan0 up
> sudo ~/hostap/hostapd/hostapd ~/hostap/hostapd/hostapd.conf -dd &!
> iperf -s -i1
> the client is set up:
> sudo rmmod ath9k ath9k_common ath9k_hw ath mac80211 cfg80211
> sudo modprobe ath9k
> sudo ifconfig wlan1 up
> sudo iwconfig wlan1 essid <essid>
> iperf -c -i1 -t 30

Oh, so if nothing else is running I don't see why this would happen. If
no traffic is lost, it would seem likely that the client is initiating
powersave though, because otherwise I'm pretty sure traffic from the
client would drop (if the AP just goes away, there's no powersave mode
for APs)


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