Re: NM suboptimal with weak signal strength, easy fix

[Dan Williams <dcbw redhat com>]

On Fri, 2007-06-01 at 14:58 -0700, Saikat Guha wrote:
> On Fri, 2007-06-01 at 17:55 -0400, Dan Williams wrote:
> > The driver is telling userspace that it has lost association with the
> > access point.  Future versions of NM will try harder to reconnect before
> > timing out, but I'm not convinced that "pinning" is the best thing to do
> > from an interaction perspective.
> 
> From the driver's perspective, it is the right thing to do to report
> lost associations.
> 
> However, the driver doesn't know whether it'll reacquire association
> soon or not; the user, however, may very well know. I suppose the driver
> or NM could employ some heuristics (extended periods of low signal
> strength = expect intermittent disassociations), which may be a better
> approach than pinning if it does the right thing at the right time.

NM doesn't kill the connection immediately; but if wpa_supplicant or the
driver can't re-establish association within about 8 seconds, NM will
kill it.

> As for NM trying harder to reconnect, what I'd see is that NM would
> re-associate, but then it would try to re-acquire the DHCP lease (even
> when it is the same network (AP mac even), and the old lease is still
> valid).

Not necessarily, since NM would know that it just lost association and
that the association has only been lost for a certain period of time, it
could just re-establish the 802.11 connection.  If the DHCP address
comes up for lease expiration while association is re-attempted, then
DHCP will likely fail the request because it can't contact the server,
but that's also catchable I guess.

> So perhaps, the fix would be to skip DHCP reacquisition if the old lease
> is still valid and you associate to the same network (ssid? ap mac?). 

Right.  But there's still some icky cases if the DHCP lease is about to
expire.

Dan