Wireless network problem with Access Point selection using ifup

Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

I have a wireless-N Linksys router centrally located in my home. I also 
have 2 each Linksys E1000 range extenders located at each end of the 
house. I have Desktop computers in fixed locations around the house. 
Using Network Manager all is well with all of them. I can see all the 
Access Points and select the one with the best signal. However network 
manager doesn't seem to be a valid option for all of them and I'm using 
traditional IFUP with static configurations.

When using IFUP, wrong Access Points are being chosen by whatever the 
underlying userland/kernel process is that is supposed to select it. It 
seems it wants to select the one with the weakest signal instead of the 
strongest.  I'm being told that when using ifup and WPA, as opposed to 
WEP, that userland has no choice in the selection of an Access Point by 
MAC address, only by SSID. All my APs have the same SSID.

I am using SuSE 12.2 Linux and 3.6.6 kernels on all these machines and 
the wireless hardware I am using on all these is are ASUS USB-300N adapters.

lsusb output: Bus 001 Device 004: ID 0b05:17ab ASUSTek Computer, Inc.

The kernel driver being used is rtl8192cu.


I don't understand why the developers of whatever the underlying 
userland/kernel process is that selects the AP, did not think that a 
user selection option by MAC address might be a good idea, as I'm told 
it is possible using WEP.  In any case, I am unable to get all this 
stuff working properly. Most of the time, the AP furthest away is 
selected. Often the router in the middle of the house is selected. Very 
very rarely is the closest AP chosen. When the furthest is chosen, I am 
unable to use the network. When the router in the middle of the home is 
selected, the connection comes to a crawl and often disassociates in the 
middle of use. When it does choose the correct AP, all is well until I 
reboot the machine.

The same thing happens with the desktop machine at the other end of the 
house but most of the time it selects the router in the middle of the 
house. It has never selected the closest AP.

Some sample dmesg and iwconfig output when the AP at the other end of 
the house was selected:


[   19.876977] wlan0: authenticate with c8:d7:19:7a:ab:1e
[   19.901616] wlan0: send auth to c8:d7:19:7a:ab:1e (try 1/3)
[   19.904099] wlan0: authenticated
[   19.916679] wlan0: associate with c8:d7:19:7a:ab:1e (try 1/3)
[   19.925839] wlan0: RX AssocResp from c8:d7:19:7a:ab:1e (capab=0x411 
status=0 aid=2)
[   19.925975] wlan0: associated
[   19.925988] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready



wlan0     IEEE 802.11bgn  ESSID:"hounschell-1"
               Mode:Managed  Frequency:2.437 GHz  Access Point: 
C8:D7:19:7A:AB:1E
               Bit Rate=150 Mb/s   Tx-Power=20 dBm
               Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
               Encryption key:off
               Power Management:off
               Link Quality=66/70  Signal level=-44 dBm
               Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
               Tx excessive retries:0  Invalid misc:9   Missed beacon:0

This AP is at the other end of the house. The network was unusable after 
this boot.

Is this likely a kernel issue? If so, I would be willing to help with it 
if I can with my configuration.

Regards
Mark

Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

I have a wireless-N Linksys router centrally located in my home. I also 
have 2 each Linksys E1000 range extenders located at each end of the 
house. I have Desktop computers in fixed locations around the house. 
Using Network Manager all is well with all of them. I can see all the 
Access Points and select the one with the best signal. However network 
manager doesn't seem to be a valid option for all of them and I'm using 
traditional ifup with static configurations.

When using ifup, wrong Access Points are being chosen by whatever the 
underlying userland/kernel process is that is supposed to select it. And 
I admit I do not know what that process is. It seems it wants to select 
the one with the weakest signal instead of the strongest.  Most of the 
time, the AP furthest away is selected. Often the router in the middle 
of the house is selected. Very very rarely is the closest AP chosen. 
When the furthest is chosen, I am unable to use the network. When the 
router in the middle of the home is selected, the connection comes to a 
crawl and often disassociates in the middle of use. When it does choose 
the correct AP, all is well until I reboot the machine.

I'm being told that when using ifup and WPA, as opposed to WEP, that 
userland has no choice in the selection of an Access Point by MAC 
address, only by SSID. All my APs have the same SSID.

I am using SuSE 12.2 Linux and 3.6.6 kernels on all these machines and 
the wireless hardware I am using on all these is are ASUS USB-300N adapters.

lsusb output: Bus 001 Device 004: ID 0b05:17ab ASUSTek Computer, Inc.

The kernel driver being used is rtl8192cu.


Some sample dmesg and iwconfig output when the AP at the other end of 
the house was selected:


[   19.876977] wlan0: authenticate with c8:d7:19:7a:ab:1e
[   19.901616] wlan0: send auth to c8:d7:19:7a:ab:1e (try 1/3)
[   19.904099] wlan0: authenticated
[   19.916679] wlan0: associate with c8:d7:19:7a:ab:1e (try 1/3)
[   19.925839] wlan0: RX AssocResp from c8:d7:19:7a:ab:1e (capab=0x411 
status=0 aid=2)
[   19.925975] wlan0: associated
[   19.925988] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready



wlan0     IEEE 802.11bgn  ESSID:"hounschell-1"
               Mode:Managed  Frequency:2.437 GHz  Access Point: 
C8:D7:19:7A:AB:1E
               Bit Rate=150 Mb/s   Tx-Power=20 dBm
               Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
               Encryption key:off
               Power Management:off
               Link Quality=66/70  Signal level=-44 dBm
               Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
               Tx excessive retries:0  Invalid misc:9   Missed beacon:0

This AP is at the other end of the house. The network was unusable after 
this boot.

Is this likely a kernel issue? If so, I would be willing to file a BUG 
report and even help with it if I can with my configuration.

Regards
Mark

Re: Wireless network problem with Access Point selection using ifup

[Johannes Berg]

On Thu, 2012-12-06 at 09:10 -0500, Mark Hounschell wrote:
>  I'm using 
> traditional ifup with static configurations.

You should at least run wpa_supplicant, which will pick a better network
and reconnect if the connection drops etc. Almost no device does that by
itself any more.

johannes

Re: Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

On 12/06/2012 10:03 AM, Johannes Berg wrote:
> On Thu, 2012-12-06 at 09:10 -0500, Mark Hounschell wrote:
>>   I'm using
>> traditional ifup with static configurations.
>
> You should at least run wpa_supplicant, which will pick a better network
> and reconnect if the connection drops etc. Almost no device does that by
> itself any more.

  wpa_supplicant is running.

#ps ax | grep wpa

wpa_supplicant -iwlan0 -c/var/run/wpa_supplicant-wlan0.conf -Dnl80211,wext 
-P/var/run/wpa_supplicant/wlan0.pid -B


When the router in the middle of the house is chosen, as opposed to the 
range extender in the very same room, the network works for a time but 
eventually disassociates, usually reason 7, and never reconnects to 
anything.

Mark

Re: Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

On 12/07/2012 05:12 AM, Mark Hounschell wrote:
> On 12/06/2012 10:03 AM, Johannes Berg wrote:
>> On Thu, 2012-12-06 at 09:10 -0500, Mark Hounschell wrote:
>>>   I'm using
>>> traditional ifup with static configurations.
>>
>> You should at least run wpa_supplicant, which will pick a better network
>> and reconnect if the connection drops etc. Almost no device does that by
>> itself any more.
>
>   wpa_supplicant is running.
>
> #ps ax | grep wpa
>
> wpa_supplicant -iwlan0 -c/var/run/wpa_supplicant-wlan0.conf
> -Dnl80211,wext -P/var/run/wpa_supplicant/wlan0.pid -B
>
>
> When the router in the middle of the house is chosen, as opposed to the
> range extender in the very same room, the network works for a time but
> eventually disassociates, usually reason 7, and never reconnects to
> anything.
>

Hi Johannes,

Thanks for responding. Do you think my problem is a wpa_supplicant 
issue, a kernel issue, or a Dist issue?

Regards
Mark

Re: Wireless network problem with Access Point selection using ifup

[Johannes Berg]

On Fri, 2012-12-07 at 15:50 -0500, Mark Hounschell wrote:
> On 12/07/2012 05:12 AM, Mark Hounschell wrote:
> > On 12/06/2012 10:03 AM, Johannes Berg wrote:
> >> On Thu, 2012-12-06 at 09:10 -0500, Mark Hounschell wrote:
> >>>   I'm using
> >>> traditional ifup with static configurations.
> >>
> >> You should at least run wpa_supplicant, which will pick a better network
> >> and reconnect if the connection drops etc. Almost no device does that by
> >> itself any more.
> >
> >   wpa_supplicant is running.
> >
> > #ps ax | grep wpa
> >
> > wpa_supplicant -iwlan0 -c/var/run/wpa_supplicant-wlan0.conf
> > -Dnl80211,wext -P/var/run/wpa_supplicant/wlan0.pid -B
> >
> >
> > When the router in the middle of the house is chosen, as opposed to the
> > range extender in the very same room, the network works for a time but
> > eventually disassociates, usually reason 7, and never reconnects to
> > anything.
> >

> Thanks for responding. Do you think my problem is a wpa_supplicant 
> issue, a kernel issue, or a Dist issue?

I'd say it's a wpa_s issue, but I can't remember any time that it didn't
reconnect after getting disconnected, so maybe there's an issue with
your driver/device that causes it to need a reset or something ... hard
to tell more without at least the supplicant log.

johannes

Re: Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

On 12/07/2012 03:54 PM, Johannes Berg wrote:

>
>> Thanks for responding. Do you think my problem is a wpa_supplicant
>> issue, a kernel issue, or a Dist issue?
>
> I'd say it's a wpa_s issue, but I can't remember any time that it didn't
> reconnect after getting disconnected, so maybe there's an issue with
> your driver/device that causes it to need a reset or something ... hard
> to tell more without at least the supplicant log.
>

I am wpa_supplicant stupid. I'll investigate and see if I can provide 
more info. I have 4 of these devices scattered about the house on Linux 
boxes. They all do the same thing. I also have 3 TV's and a windows 
laptop my wife uses that all connect properly to it's closest AP. As you 
can see this is a project to make the whole house wireless.

Also, personally I'm more concerned as to why the Linux boxes don't just 
pick the closest AP to begin with. If it did, and it actually has, it 
never disconnects and will be reliable until a reboot.

Thanks
Mark

Re: Wireless network problem with Access Point selection using ifup

[Johannes Berg]

On Mon, 2012-12-10 at 05:15 -0500, Mark Hounschell wrote:

> I have more info. Attached are 3 files. One for each of the APs selected. 
> The furthest away, the router in the middle and even one for the 
> closest/correct AP. In each file is the logfile for wpa_s with the -dd 
> option added, the dmesg output for that particular boot, and the iwconfig 
> output.

You seem to have driver issues. After getting disconnected (for some
reason, but this isn't surprising), you get:

wlan0: State: COMPLETED -> DISCONNECTED
...
Scan requested (ret=0) - scan timeout 30 seconds
nl80211: Event message available
nl80211: Scan trigger
Scan timeout - try to get results

^ timeout here

wlan0: Event SCAN_RESULTS (3) received
nl80211: Received scan results (0 BSSes)
wlan0: BSS: Start scan result update 3
wlan0: New scan results available
wlan0: Selecting BSS from priority group 0
wlan0: No suitable network found
wlan0: Setting scan request: 5 sec 0 usec
wlan0: Checking for other virtual interfaces sharing same radio (phy0) in event_scan_results
Scan SSID - hexdump_ascii(len=12):
     68 6f 75 6e 73 63 68 65 6c 6c 2d 31               hounschell-1    
wlan0: Starting AP scan for wildcard SSID
nl80211: Scan SSID - hexdump_ascii(len=12):
     68 6f 75 6e 73 63 68 65 6c 6c 2d 31               hounschell-1    
nl80211: Scan SSID - hexdump_ascii(len=0): [NULL]
nl80211: Scan trigger failed: ret=-16 (Device or resource busy)

^ new trigger fails


So whatever driver you're using seems to be broken.

johannes

Re: Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

On 12/10/2012 05:26 AM, Johannes Berg wrote:
> On Mon, 2012-12-10 at 05:15 -0500, Mark Hounschell wrote:
>
>> I have more info. Attached are 3 files. One for each of the APs selected.
>> The furthest away, the router in the middle and even one for the
>> closest/correct AP. In each file is the logfile for wpa_s with the -dd
>> option added, the dmesg output for that particular boot, and the iwconfig
>> output.
>
> You seem to have driver issues. After getting disconnected (for some
> reason, but this isn't surprising), you get:
>
> wlan0: State: COMPLETED -> DISCONNECTED
> ...
> Scan requested (ret=0) - scan timeout 30 seconds
> nl80211: Event message available
> nl80211: Scan trigger
> Scan timeout - try to get results
>
> ^ timeout here
>
> wlan0: Event SCAN_RESULTS (3) received
> nl80211: Received scan results (0 BSSes)
> wlan0: BSS: Start scan result update 3
> wlan0: New scan results available
> wlan0: Selecting BSS from priority group 0
> wlan0: No suitable network found
> wlan0: Setting scan request: 5 sec 0 usec
> wlan0: Checking for other virtual interfaces sharing same radio (phy0) in event_scan_results
> Scan SSID - hexdump_ascii(len=12):
>       68 6f 75 6e 73 63 68 65 6c 6c 2d 31               hounschell-1
> wlan0: Starting AP scan for wildcard SSID
> nl80211: Scan SSID - hexdump_ascii(len=12):
>       68 6f 75 6e 73 63 68 65 6c 6c 2d 31               hounschell-1
> nl80211: Scan SSID - hexdump_ascii(len=0): [NULL]
> nl80211: Scan trigger failed: ret=-16 (Device or resource busy)
>
> ^ new trigger fails
>
>
> So whatever driver you're using seems to be broken.
>
> johannes
>
>

The driver is use has was identified in the original email. So I guess this 
is the right place to report this issue? In each of the wpa log files I See 
in the beginning, a section like this:

nl80211: Received scan results (4 BSSes)
wlan0: BSS: Start scan result update 1
wlan0: BSS: Add new id 0 BSSID c8:d7:19:7a:ab:1e SSID 'hounschell-1'
wlan0: BSS: Add new id 1 BSSID 20:aa:4b:b2:dd:79 SSID 'hounschell-1'
wlan0: BSS: Add new id 2 BSSID 00:18:f8:ff:72:d5 SSID 'hounschell-1'
wlan0: BSS: Add new id 3 BSSID 00:1a:70:6d:99:50 SSID 'MACDONALD'

Every time the first one listed is the one actually selected and each time 
is different and usually NOT the closest. Why? This machine is NOT roaming. 
It is a Desktop in a fixed location. The AP is within 15ft of the ASUS USB 
adapter and in direct line of sight.  There may be more than one problem 
here. I think one of the problems is right here. Above 20:aa:4b:b2:dd:79 is 
the closest AP. Why is it not first in the list? Why, when it selects one 
of the others and it can't figure out it selected the wrong one and 
reselect the right one seems like a different problem. After all when it 
does select the correct one, all is good but the actual bandwidth.

Mark

Re: Wireless network problem with Access Point selection using ifup

[Johannes Berg]

On Mon, 2012-12-10 at 06:10 -0500, Mark Hounschell wrote:

> The driver is use has was identified in the original email. So I guess this 
> is the right place to report this issue? 

Yeah, I guess Larry should take a look.

> In each of the wpa log files I See 
> in the beginning, a section like this:
> 
> nl80211: Received scan results (4 BSSes)
> wlan0: BSS: Start scan result update 1
> wlan0: BSS: Add new id 0 BSSID c8:d7:19:7a:ab:1e SSID 'hounschell-1'
> wlan0: BSS: Add new id 1 BSSID 20:aa:4b:b2:dd:79 SSID 'hounschell-1'
> wlan0: BSS: Add new id 2 BSSID 00:18:f8:ff:72:d5 SSID 'hounschell-1'
> wlan0: BSS: Add new id 3 BSSID 00:1a:70:6d:99:50 SSID 'MACDONALD'
> 
> Every time the first one listed is the one actually selected and each time 
> is different and usually NOT the closest.

That's expected, the order is random by the order in which it was found
in scanning etc. There's no inherent order here.

> It is a Desktop in a fixed location. The AP is within 15ft of the ASUS USB 
> adapter and in direct line of sight.  There may be more than one problem 
> here. I think one of the problems is right here. Above 20:aa:4b:b2:dd:79 is 
> the closest AP. Why is it not first in the list? 

See above.

> Why, when it selects one 
> of the others and it can't figure out it selected the wrong one and 
> reselect the right one seems like a different problem. After all when it 
> does select the correct one, all is good but the actual bandwidth.

Well so I suspect the driver is also not reporting useful signal
strength so that wpa_s doesn't know which one to select. And then when
the connection fails, the driver is refusing scanning so it can't even
reconnect to a better AP ...

IOW, all driver problems, and I'm not familiar enough with that driver
to tell you what's going on.

johannes

Re: Wireless network problem with Access Point selection using ifup

[Mark Hounschell]

On 12/10/2012 06:29 AM, Johannes Berg wrote:
> On Mon, 2012-12-10 at 06:10 -0500, Mark Hounschell wrote:
>
>> The driver is use has was identified in the original email. So I guess this
>> is the right place to report this issue?
>
> Yeah, I guess Larry should take a look.
>
>> In each of the wpa log files I See
>> in the beginning, a section like this:
>>
>> nl80211: Received scan results (4 BSSes)
>> wlan0: BSS: Start scan result update 1
>> wlan0: BSS: Add new id 0 BSSID c8:d7:19:7a:ab:1e SSID 'hounschell-1'
>> wlan0: BSS: Add new id 1 BSSID 20:aa:4b:b2:dd:79 SSID 'hounschell-1'
>> wlan0: BSS: Add new id 2 BSSID 00:18:f8:ff:72:d5 SSID 'hounschell-1'
>> wlan0: BSS: Add new id 3 BSSID 00:1a:70:6d:99:50 SSID 'MACDONALD'
>>
>> Every time the first one listed is the one actually selected and each time
>> is different and usually NOT the closest.
>
> That's expected, the order is random by the order in which it was found
> in scanning etc. There's no inherent order here.
>
>> It is a Desktop in a fixed location. The AP is within 15ft of the ASUS USB
>> adapter and in direct line of sight.  There may be more than one problem
>> here. I think one of the problems is right here. Above 20:aa:4b:b2:dd:79 is
>> the closest AP. Why is it not first in the list?
>
> See above.
>
>> Why, when it selects one
>> of the others and it can't figure out it selected the wrong one and
>> reselect the right one seems like a different problem. After all when it
>> does select the correct one, all is good but the actual bandwidth.
>
> Well so I suspect the driver is also not reporting useful signal
> strength so that wpa_s doesn't know which one to select. And then when
> the connection fails, the driver is refusing scanning so it can't even
> reconnect to a better AP ...
>
> IOW, all driver problems, and I'm not familiar enough with that driver
> to tell you what's going on.
>

Should I file and bug report and/or contact the author?

Mark