channel_policy

[Boris]

Chuck Tuffli schrieb:
>> -----Original Message-----
>> From: hostap-bounces at lists.shmoo.com 
>> [mailto:hostap-bounces at lists.shmoo.com] On Behalf Of Boris
>> Sent: Tuesday, July 22, 2008 2:44 AM
>> To: hostap at lists.shmoo.com
>> Subject: channel_policy
>>
> ...
>> Because I had a lot of troubles associating with the AP even 
>> unencrypted, I borrowed a Belkin AP as a reference. I found 
>> out that it seems that channel 1 is extremely noisy and I 
>> should switch to channel 7 or 8.
> 
> Assuming you are using 2.4GHz frequencies, the 3 non-overlapping
> channels are 1, 6, and 11. Using 7 and 8 will avoid channel 1, but this
> won't help you if channel 6 is busy.
> 
> What is the output of 'iwlist ath0 freq' ?

Hej Chuck,

first thanks a lot for caring about my stuff!

Is it common here to answer to list AND sender? I will try to do...

Yes, you are right: I am doing all this in Germany and we are talking
about 2.4 GHz range.

With the Belkin router, I switched through all the channels and found
out that link quality differs a lot between channel 1 (12/70) to 11
(63/70). Channels 7 and 8 seem optimal, while channels 6, 9 an 11 are
used by different APs:

# iwlist ath0 scan | grep Freq
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.462 GHz (Channel 11)
                    Frequency:2.452 GHz (Channel 9)
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.462 GHz (Channel 11)
                    Frequency:2.462 GHz (Channel 11)

I should add that the distance between my AP and Laptop is less than two
meters without any electromagnetic barriers or walls or something.

As we are talking about leaf, I have no madwifi-tools or wireless-tools
on the Alix box I want to use as AP.

But on my laptop, iwlist ath0 freq gives me:

ath0      22 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Current Frequency=2.412 GHz (Channel 1)

I can disalbe wpa and start hostapd on the AlixBox with this
/etc/hostapd/hostapd.conf:

interface=ath0
driver=madwifi
logger_syslog=-1
logger_stdout=-1
logger_stdout_level=0
debug=4
ctrl_interface=/var/run/hostapd
# ctrl_interface_group=0
ssid=gartenstr
hw_mode=g
#channel_policy=2
channel=8
macaddr_acl=0         # 1 = deny unless in accept list
auth_algs=3
ignore_broadcast_ssid=0
#wpa=3
#wpa_psk=schoenwohnenundsicherfunkeninderGartenstrasse_27_machtvielSpass
#####wpa_passphrase=schoenwohnenundsicherfunkeninderGartenstrasse_27_machtvielSp#wpa_key_mgmt=WPA-PSK
#wpa_pairwise=TKIP CCMP
#####eap_authenticator=0
#####eap_message=Moin
#eap_server=0
#eapol_key_index_workaround=0
#####own_ip_addr=127.0.0.1

Now iwconfig with the laptop brings me:

ath0      IEEE 802.11g  ESSID:"gartenstr"  Nickname:""
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:80:48:54:85:81
          Bit Rate:54 Mb/s   Tx-Power:23 dBm   Sensitivity=1/1
          Retry:off   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=15/70  Signal level=-43 dBm  Noise level=-58 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

So the AP actually works on channel 1. Basically, the problem is the bad
link quality which lets the association break down after some seconds.
But that confirms what I found out with the Belkin: 2.412 GHz seems very
noisy.....

Hope that helps helping me! :-)

Boris