[maemo-users] WLAN PSM and Strange disconnects from wifi

From: Bad Dog baddog at uniblab.com
Date: Tue Mar 6 19:31:09 EET 2007
I have been experiencing disconnects from the local ISP's wireless
network.  I wrote asking for help last week, but didn't have enough
information to really diagnose things.

Yesterday, I got a packet trace from a laptop and looked at the syslogd
output on the N800.  No joy there.

>From what I can tell, the N800 connects just fine, but then the ISP's
router disconnects after a few seconds..  I have used both their
captive-portal login (mikrotik) and have had them switch me to MAC
address filtering, but there is no difference in the disconnect.  

They use Tropos routers.  The have established a policy where they send
broadcast ARP requests to see who is out there.  Once someone is
authenticated either by MAC address or through the portal, they send
unicast APR messages as a keepalive.  If you miss a small number of
these, then you are considered "offline".  

The packet trace shows responses to unicast ARP from the N800, so that
is not the problem.  I see several of them.  Also, if I keep other kinds
of traffic going to and from the device, like making many http requests
or running internet radio, then it stays up.  If I don't do that, and
instead just do an rss feed update or read one web page for too long, I
am disconnected.

This is NOT an issue with my debian-based laptop, nor any other wifi
devices the ISP has seen.  So, I suspect configuration or hardware

Given all that, my question is this... is it possible that
power-saving-mode is the culprit?  What happens during power save mode?
Which protocols will wake it back up, which won't?  Does it just drop
the power level, or does it stop traffic of any or certain types?

The packet trace showed nothing out of the ordinary, other than some
stray tcp fragments resulting from the disassociation from the router.
The syslogd trace showed the same things that happen during a successful
connection to a different network.

The same things happens on my 770.

Any ideas appreciated.

I am not really familiar with gconfd, so I would be obliged if someone
can share the right shell incantation to change the power saving mode


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