For a while now, I've been experiencing connection stability issues which from
what I can tell seem to stem from the use of dhclient.
After upgrading to the latest wireless-testing kernel, I noticed the output from
wpa_supplicant and iwconfig regarding association status differed as well as an
inability to use dhclient to receive an ip address. In an attempt to resolve
the issue, I first eliminated the use of dhclient by issuing a static ip address
for the interface after it was associated with the AP. Doing so resulted in a
very
stable and reliable connection. This led me to believe the issues were a result
of using dhclient. To verify, I tried dhcpcd in place of dhclient, which once
again
resulted in a stable and reliable connection. Thus confirming my suspicion.
While examining the behavior of dhclient and dhcpcd, I maintained a copy of the
resulting dmesg output that was produced for comparison. The results of which,
as
shown below, seem to indicate dhclient is causing the interface to be removed
and
then re-added. While I can only speculate at why this happens, I think it may be
related to the fact that dhclient tries to broadcast on all interfaces related
to the one that was specified. Thus the command: "dhclient wlan0", causes
dhclient
to broadcast on wmaster0, moni0(when configured), and wlan0.
Despite the information in demsg, when dhclient is used wpa_supplicant seems to
maintain information that it is associated with the AP while iwconfig indicates
otherwise. In any case, the interface enters a state that seems to confuse
wpa_supplicant. Thus wpa_supplicant needs to be restarted or the AP needs to be
explicitly specified using iwconfig wlan0 ap .
While dhclient may clearly be at fault here, I have observed similar behavior
on
2.6.25-wl as well as prior kernels. With 2.6.25-wl the output from both
"wpa_cli status"
and "iwconfig wlan0" indicate there is an association with the AP, when it is
apparent
there is not as a result of the removal and addition of the interface by
dhclient. In
which case, issuing a static ip address to the interface after attempting to
use dhclient
results in transmission timeouts while trying to ping another node on the
network.
Thus indicating that the interface is indeed not associated as otherwise
indicated.
Regards,
David Ellingsworth
Output from "uname -r": 2.6.26-rc4-wl
Output from "lspci -vvn":
==================================================================================
00:09.0 0280: 14e4:4320 (rev 02)
Subsystem: 0e11:00e7
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping-
SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast>TAbort- SERR-
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