wpa-supplicant v0.7.2 stops roaming after a while

Michel Marti mma at objectxp.com
Wed Apr 28 10:41:35 EDT 2010


Hi,

I noticed that after running for a while, wpa-supplicant (v0.7.2) stops roaming to a
better AP altough the scan results clearly contain a (much) stronger AP.

Driver in use is madwifi (latest from 0.9.4 branch). I have set the background scan
interval on the card to 30 seconds (iwpriv ath0 bgscanintvl 30).

My wpa_supplicant configuration looks like this:

--------------------------------------
ctrl_interface=/var/run/wpa_supplicant
network={
	ssid="4YEO"
	psk="****************"
}
--------------------------------------

Output from wpa_cli status
--------------------------
Selected interface 'ath0'
bssid=00:18:39:d4:63:a4
ssid=4YEO
id=0
mode=station
pairwise_cipher=CCMP
group_cipher=TKIP
key_mgmt=WPA2-PSK
wpa_state=COMPLETED
ip_address=192.168.0.233

Output from 'wpa_cli scan_results'
----------------------------------
bssid / frequency / signal level / flags / ssid
00:15:70:56:ff:90	2437	175	[WPA2-PSK-CCMP][ESS]	4YEO
00:18:39:d4:63:a4	2462	233	[WPA-PSK-TKIP+CCMP][WPA2-PSK-TKIP+CCMP][ESS]	4YEO
[snip...]

Output from wpa-supplicant
--------------------------
1272463876.364773: RTM_NEWLINK: operstate=1 ifi_flags=0x11043 ([UP][RUNNING][LOWER_UP])
1272463876.364912: Wireless event: cmd=0x8b19 len=8
1272463876.365360: Received 1727 bytes of scan results (8 BSSes)
1272463876.365502: BSS: Start scan result update 56
1272463876.365622: New scan results available
1272463876.365742: RSN: Ignored PMKID candidate without preauth flag
1272463876.365826: Selecting BSS from priority group 0
1272463876.366019: Try to find WPA-enabled AP
1272463876.366087: 0: 00:18:39:d4:63:a4 ssid='4YEO' wpa_ie_len=28 rsn_ie_len=24 caps=0x11
1272463876.366186:    selected based on RSN IE
1272463876.366247:    selected WPA AP 00:18:39:d4:63:a4 ssid='4YEO'
1272463876.366320: Considering within-ESS reassociation
1272463876.366376: Current BSS: 00:18:39:d4:63:a4 level=234
1272463876.366436: Selected BSS: 00:18:39:d4:63:a4 level=234
1272463876.366496: Skip roam - too small difference in signal level

=> Why does wpa-supplicant not consider the AP with BSS 00:15:70:56:ff:90?!?


After restarting wpa_supplicant, roaming again works as expected:

Output from 'wpa_cli scan_results'
----------------------------------
00:18:39:d4:63:a4	2462	211	[WPA-PSK-TKIP+CCMP][WPA2-PSK-TKIP+CCMP][ESS]	4YEO
00:15:70:56:ff:90	2437	223	[WPA2-PSK-CCMP][ESS]	4YEO
[snip...]

Output from wpa-supplicant
--------------------------
1272464360.315564: RTM_NEWLINK: operstate=1 ifi_flags=0x11043 ([UP][RUNNING][LOWER_UP])
1272464360.315704: Wireless event: cmd=0x8b19 len=8
1272464360.316148: Received 1727 bytes of scan results (8 BSSes)
1272464360.316294: BSS: Start scan result update 7
1272464360.316415: New scan results available
1272464360.316803: RSN: Ignored PMKID candidate without preauth flag
1272464360.316900: Selecting BSS from priority group 0
1272464360.316955: Try to find WPA-enabled AP
1272464360.317012: 0: 00:15:70:56:ff:90 ssid='4YEO' wpa_ie_len=0 rsn_ie_len=20 caps=0x11
1272464360.317104:    selected based on RSN IE
1272464360.317164:    selected WPA AP 00:15:70:56:ff:90 ssid='4YEO'
1272464360.317239: Considering within-ESS reassociation
1272464360.317295: Current BSS: 00:18:39:d4:63:a4 level=211
1272464360.317354: Selected BSS: 00:15:70:56:ff:90 level=220
1272464360.317492: Trying to associate with 00:15:70:56:ff:90 (SSID='4YEO' freq=2437 MHz)


Any Idea on what is going wrong here?

Thanks,
- Michel



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