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<TITLE>RE: Multicast with Linksys PCI WMP11 AP and PCMCIA WPC 11 ver 3</TITLE>
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<P><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> On Wed, Nov 27, 2002 at 10:10:14AM -0500, Bichot Guillaume </FONT>
<BR><FONT SIZE=2>> (Princeton) wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> > I'm making some measurement in multicast/broadcast mode having one </FONT>
<BR><FONT SIZE=2>> > server sending some multicast UDP traffic through a Linksys </FONT>
<BR><FONT SIZE=2>> WMP 11 PCI </FONT>
<BR><FONT SIZE=2>> > - Hostap - AP. The client is either the ipaq 3850 under </FONT>
<BR><FONT SIZE=2>> Familiar 0.5.3 </FONT>
<BR><FONT SIZE=2>> > or a laptop under Linux redhat 8.0. Both uses a Linksys WPC </FONT>
<BR><FONT SIZE=2>> 11 PCMCIA </FONT>
<BR><FONT SIZE=2>> > card (manfid 0x274, 0x1613).</FONT>
<BR><FONT SIZE=2>> > </FONT>
<BR><FONT SIZE=2>> > With the ipaq:</FONT>
<BR><FONT SIZE=2>> > The hostap driver simply does not work with the linksys card (it </FONT>
<BR><FONT SIZE=2>> > supposed to work with this card). I got the following error:</FONT>
<BR><FONT SIZE=2>> > hostap_cs: card initialization timed out</FONT>
<BR><FONT SIZE=2>> > Hostap_cs: initialization failed</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Does the same linksys card work in the laptop? Linksys WPC11 </FONT>
<BR><FONT SIZE=2>> Ver3 should work fine with Host AP driver, but I have not </FONT>
<BR><FONT SIZE=2>> tested the latest version of the driver with ARM platform. Do </FONT>
<BR><FONT SIZE=2>> you see any other error messages in the kernel log ('dmesg')?</FONT>
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<P><FONT SIZE=2>[Guilaume] Yes the same linksys card works with the laptop. </FONT>
<BR><FONT SIZE=2>It used to work with an old IPAQ though many Tx timeouts(ipaq 3635 , bootldr 2.18.01, Familiar 0.5.3). It does not work with the current one (ipaq 3870, bootldr 2.18.54, Familiar 0.5.3)</FONT></P>
<P><FONT SIZE=2>Extra messages are (I do not have dmesg in the ipaq):</FONT>
<BR><FONT SIZE=2>Wlan0: hfa384x_set_rid - to BAPA0 failed</FONT>
<BR><FONT SIZE=2>hostap_cs: wlan0: resetting card</FONT>
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<P><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> > With the laptop:</FONT>
<BR><FONT SIZE=2>> > The average association time (i.e. the client detects and </FONT>
<BR><FONT SIZE=2>> associates </FONT>
<BR><FONT SIZE=2>> > with the AP)is 10 seconds between 256 Kbit/s and 1 Mbit/s. With a </FONT>
<BR><FONT SIZE=2>> > 2Mbit/s throughput it becomes impossible to associate with the AP.</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Lot of date traffic in the network will result in association </FONT>
<BR><FONT SIZE=2>> problems since most stations seem to use quite strict limits </FONT>
<BR><FONT SIZE=2>> on how long time receiving of the auth/assoc reply can take. </FONT>
<BR><FONT SIZE=2>> If you upgrade your AP to use latest CVS version, you should </FONT>
<BR><FONT SIZE=2>> be able to see whether the station is acknowledging </FONT>
<BR><FONT SIZE=2>> auth/assoc replies (if not, the delay was probably too long).</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> At the moment, the driver does not prioritize outgoing frames </FONT>
<BR><FONT SIZE=2>> at all, but I might need to do this at some point to help </FONT>
<BR><FONT SIZE=2>> association under heavy load. It should help, if the AP would </FONT>
<BR><FONT SIZE=2>> simply by-pass any outgoing queue of data frames when sending </FONT>
<BR><FONT SIZE=2>> auth/assoc replies. There can still be some frames buffered </FONT>
<BR><FONT SIZE=2>> in the wlan card, but at least the host-side queue would not </FONT>
<BR><FONT SIZE=2>> be adding latency. In addition, number of buffered frames in </FONT>
<BR><FONT SIZE=2>> the wlan card could be reduced, if needed.</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> > I've tried the iwpriv command to decrease the beacon period </FONT>
<BR><FONT SIZE=2>> but I got </FONT>
<BR><FONT SIZE=2>> > the</FONT>
<BR><FONT SIZE=2>> > following: </FONT>
<BR><FONT SIZE=2>> > </FONT>
<BR><FONT SIZE=2>> > # iwpriv wlan0 prism2_param wlan0 beacon_int 1</FONT>
<BR><FONT SIZE=2>> > # Interface doesn't accept private ioctl</FONT>
<BR><FONT SIZE=2>> > # prism2_param (8BE0): Operation not supported</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> That command is not correct. It should be either 'iwpriv </FONT>
<BR><FONT SIZE=2>> wlan0 beacon_int #' or 'prism2_param wlan0 beacon_int #' (if </FONT>
<BR><FONT SIZE=2>> iwpriv/wireless_ext does not support extended iwpriv </FONT>
<BR><FONT SIZE=2>> commands). In addition, you should note that setting beacon </FONT>
<BR><FONT SIZE=2>> interval to 1 would mean that the AP would be sending about </FONT>
<BR><FONT SIZE=2>> 1000 beacons per second in addition to all other traffic and </FONT>
<BR><FONT SIZE=2>> that might already be enough to prevent association..</FONT>
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<P><FONT SIZE=2>Thanks. Sure 1 is not exactly the good value.</FONT>
<BR><FONT SIZE=2>Currently I'm running wvlan_cs that is the only driver that works with my ipaq (orinoco_cs does not work). I've constated a 20% packet loss in multicast whatever the bit rate.</FONT></P>
<P><FONT SIZE=2>Guillaume</FONT>
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