[2008.9] Wifi very unreliable

Matthias Apitz guru at unixarea.de
Thu Oct 2 19:41:13 CEST 2008

El día Thursday, October 02, 2008 a las 04:39:01PM +0100, Alastair Johnson escribió:

> vale wrote:
> > add a sleep 500 to your loop ;)  

I run this script for an hour or so:

root at om-gta02:~# cat wifi.sh 
cd /tmp
while true; do

    rm 1M
    wget http://www.unixarea.de/1M
    date ; echo -n "now sleeping 300 sec ... "
    sleep 300
    echo awaked


and there has been no problem all this time; as well ifconfig does not
show any error packets:

root at om-gta02:~# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:12:CF:8E:FC:5F  
          inet addr:  Bcast: Mask:
          inet6 addr: fe80::212:cfff:fe8e:fc5f/64 Scope:Link
          RX packets:302728 errors:0 dropped:0 overruns:0 frame:0
          TX packets:131532 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:454345265 (433.2 MiB)  TX bytes:10145574 (9.6 MiB)

and if you compare the RX/TX values with those from the last post:

          RX packets:285483 errors:0 dropped:0 overruns:0 frame:0
          TX packets:121870 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:431367301 (411.3 MiB)  TX bytes:9439240 (9.0 MiB)

you see that moving from office to my home, i.e. from one AP to another,
I did not rebooted; I just ifdow / ifup with my script the eth0

> > 
> > which image / kernel are you using?
> You should perhaps ask what AP he's using, or whether he has the power 
> management enabled on the wifi. Some APs apparently get upset by power 
> managed devices, and the Freerunner enables power management of the wifi 
> by default to preserve battery. My wrt54g certainly gets upset from time 
> to time if I connect with the freerunner, sometimes refusing to talk to 
> _anything_ over wifi afterwards until rebooted.

my AP at home is a SMCWBR14-G2 EU one; regardless of the FR already in
the past sometime this get stuck and needs a power-cycle; not during the
test today;

the actual iwconfig values are:

# iwconfig eth0
eth0      AR6000 802.11g  ESSID:"tarara"  
          Mode:Managed  Frequency:2.442 GHz  Access Point: 00:13:F7:0D:08:48   
          Bit Rate=54 Mb/s   Tx-Power=15 dBm   Sensitivity=0/3  
          Encryption key:XXXXXXXXXXXXX  Security mode:open
          Power Management:off
          Link Quality:207/94  Signal level:-144 dBm  Noise level:-96 dBm
          Rx invalid nwid:0  Rx invalid crypt:1487  Rx invalid frag:0
          Tx excessive retries:55  Invalid misc:0   Missed beacon:64



Matthias Apitz
Manager Technical Support - OCLC GmbH
Gruenwalder Weg 28g - 82041 Oberhaching - Germany
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