ap scanning?

Daniel Halperin dhalperi
Wed May 4 07:08:17 PDT 2011

On Wed, May 4, 2011 at 1:50 AM, Johannes Berg <johannes at sipsolutions.net> wrote:
> 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)

hmmmm, yeah, that's my thinking too, but I can't for the life of me
figure out what would be doing this. Both sides of the link claim (via
iwconfig) that "Power management: off". The gap is nearly exactly 2
seconds, for which there is nothing logged in syslog on either machine
even though I have debug prints at the mac80211 entry points for all
the rate selection functions. Neither side reports lost packets.

I set up 3 extra terminal windows running at the same time, and pinged
an external wired machine and across the wireless link every 0.2s, and
the wired pings showed no disruption, while the wireless pings showed
a 2s gap in te same place. So, the problem does appear to be limited
to the wireless link.

Any ideas what would cause the wireless link to sleep for exactly 2s?


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