[Gumstix-users] AP mode is not reliable, Linux: 2.6.39, IEEE 802.11g mode, Gumstix AirStorm

[LP/李 <li...@lp...>]

Dear all:

Last years, I have aseked the same question. I have deleted that question. 
I will update the question.
 
Forgiving my interruption please. I really have a difficult problem.
 
The following is the details of my problem. 
Can anybody help kindly? 
Your advise is highly appreciated.
 
++++++++++++++++++++++++++++++++++++++++++++++++ 
Type of Gumstix:        GS3703A AirStrom R3576 
Version of kernel:       2.6.39
hostapd :   0.72
dhcp:   4.2.4-P2
 
I have made the Gumstix work as an Access Point according the following page.
 http://corysohrakoff.wordpress.com/2011/09/13/enabling-wifi-ap-mode-on-a-gumstix-overo/
The Access point can work in both IEEE 802.11b and IEEE 802.11g mode.
It works pretty well in IEEE 802.11b mode.
 
Unfortunately, it is not reliable while working in IEEE802.11g mode.
 For example, a PC is associated to the access point. 
    And the PC sends data to Access point. Commonly, the size of the data is about 20Mbyte. 
 In this case, the Access Point is vulnerable. It often fails.
 The link between the PC and Access point is down.
 The PC can find the SSID of the Acess point. 
 However, the PC can not reassociate to the Access point. 
 
In this case, we have checked the system log of Gumstix. There is no relevant error log.


I also check the current module, they are
---------------------------------------
root@overo:~# lsmod
Module                  Size  Used by
bnep                   13540  2
hci_uart               22229  3
bridge                 71666  0
stp                     1849  1 bridge
llc                     4886  2 bridge,stp
libertas_tf_sdio        8845  0       //firmware for wireless module
firmware_class          6575  1 libertas_tf_sdio  
libertas_tf            15513  1 libertas_tf_sdio  //firmware for wireless module
mac80211              169685  1 libertas_tf
rfcomm                 57984  9
cfg80211              150173  1 mac80211
ipv6                  246305  15 bridge
option                 13711  0
hidp                   17208  0
bluetooth             191991  24 bnep,hci_uart,rfcomm,hidp
usb_wwan               11545  1 option
ftdi_sio               29090  0
rfkill                 16931  3 cfg80211,bluetooth
usbserial              32737  3 option,usb_wwan,ftdi_sio
ads7846                10484  0
root@overo:~#
---------------------------------------
It seems that all the modules are OK.




I also check the current process
----------------------------------------
root@overo:~# ps ax
  PID TTY      STAT   TIME COMMAND
......
  586 ?        S<     0:00 [cfg80211]
  607 ?        S<     0:00 [libertastf]            //fireware
  612 ?        S<     0:00 [libertas_tf_sdi]          //firmware
  768 ?        S<s    0:00 /usr/local/bin/hostapd -B /etc/hostapd.conf    //Access point soft
  771 ?        S<s    0:00 /usr/local/sbin/dhcpd -cf /etc/dhcp/dhcpd.conf   //dhcp soft
  798 ?        Ss     0:00 dhclient -v -pf /var/run/dhclient.br0.pid -lf /var/lib/dhcp/dhclient.br0.leases br0
.............
  981 ?        S<s    0:00 /usr/sbin/bluetoothd --udev
  985 ?        S      0:00 /usr/bin/rfcomm -r watch 0 1 /sbin/getty -w -L rfcomm0 115200 vt100
  995 ?        S      0:00 /usr/sbin/lighttpd -f /etc/lighttpd.conf
 1005 ttyO2    S+     0:00 ftp
 1006 ?        Ss     0:00 sshd: root@pts/0
 1008 pts/0    Ss     0:00 -sh
...............
root@overo:~#
---------------------------------------- 
The above are network process.
It seems that there is no error.
 
 Only if the Access Point is rebooted, the PC can reassociate to AP.
 

We have tried to use 
 hostapd :   0.73  // the above problem exists too.
 hostapd :   1.0.0  // Gumstix can not work in access point mode.
         //

We have used  Gumstix FireStorm and Fire. We met the save problem.

FTP is used to transmit data from PC to Gumstix. Sometimes, our own program is used to transmit.
In both case, the above problem takes place.
 
++++++++++++++++++++++++++++++++++++++++++++++++
 
The problem has puzzled me for a long time.
Can you help me?
Thanks a lot in advance.