From: Helmut Schaa <helmut.schaa@googlemail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH] mac80211: use beacons for connection monitoring
Date: Thu, 30 Jul 2009 11:36:39 +0200
Cc: Reinette Chatre <reinette.chatre@intel.com>,
	linville@tuxdriver.com, linux-wireless@vger.kernel.org
References: <1248903159-17024-1-git-send-email-reinette.chatre@intel.com> <1248903902.8925.1.camel@johannes.local>
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Am Mittwoch, 29. Juli 2009 schrieb Johannes Berg:
> On Wed, 2009-07-29 at 14:32 -0700, Reinette Chatre wrote:
> > From: Reinette Chatre <reinette.chatre@intel.com>
> > 
> > The connection monitor currently relies on probe requests paired
> > with probe responses to ensure that a connection is alive. This is
> > fragile in some environments where probe responses can get lost.
> > When we receive beacons we can also consider the connection to be
> > alive, so cancel connection poll instance when we receive a beacon.
> > 
> > The debug message "cancelling probereq poll due to a received beacon"
> > is removed as part of this change as this case is hit very often after
> > the above change and debug log receives significant number of these messages.
> 
> Not doing that was actually intentional -- we want to know whether or
> not the connection is working both ways, not just whether we can receive
> frames. This can certainly be improved, but I'm not sure this is the
> best approach.

Just out of curiosity, do direct probe requests get ACKed?

If not, the hardware wouldn't have a possibility to retry the frame and the
probability of loosing a probe request frame would be much higher then of
a data frame.

Helmut