strange wifi client behavior

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Mar 27th, 2008
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i've a situation where i can't associate to the lightweight ap near to the pc but is able to associate to other laps in the 4th and 3rd floors. when i try to remove the mac from the lap (via the wlc), it just transfers to another lap but not to the one i'm near at.


i disabled the radio of the far laps from 4th and 3rd floors where the pc is hopping from. finally it got associated to the supposed lap, and the signal from this is 'Excellent'.


The signal from the 4th and 3rd floor, when the pc is connected, is really weak, compared to when it is connected to the nearby lap. about 2 bars on the status.


after i enabled the radios of the laps, the pc associated back to the lap in the 4th floor, which is having 25 (level 3) of power and on channel 6. the channel of the nearby ap is 11. and having the same power level (3).


any ideas why this is happening?




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john.preves Thu, 03/27/2008 - 10:49
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There could be a book written speculating on why it is happening. Building contsruction, interference, multipath, loose antenna connection, bad AP, not living right or holding your tongue the right way...on and on like that.


What I would do to attempt to fix it would be to survey all the power settings at all the channels and see what catches my eye. Ideally, you want the client to associate to the AP in the vacinity and not one upstairs etc..You do this by utilizing smaller cells and lower power, possibly even directional antennas, but probably not just yet.


If the signal upstairs is just as good as the signal downstairs the power is too high. I accept a certain amount of bleed through but in these situations I try to put AP's directly on top of one another (different channels of course) to give the client the best shot at staying connected to the one I want. The AP further away has to be a less desirable target then the one you want...

Richard Atkin Thu, 04/03/2008 - 11:56
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The act of associating to an Access Point is controlled by the client. I'd suggest you update your client drivers and try again.

pirateoftheairwaves Fri, 04/04/2008 - 22:14
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Unfortunately, there is no driver update for the wic since 2004. and tweaking the Advanced Properties of the wic didn't help. available options are RTS threshold (which is the same with the WLC), Preamble (i chose long, for client and WLC), power, 802.11 modes.



Scott Fella Sat, 04/05/2008 - 07:59
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Have you looked at how other clients are working in this envorionment..... I would have to say if you can isolate the issue to a certain device and that there is no latest updates, that you recommend that the wireless cards be replaced. It seems to be your only solution at this time.

pirateoftheairwaves Sun, 04/06/2008 - 04:40
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hi fella5,


i forgot to mention in the other thread, (FAT Tx Power & THIN Tx Power Levels) that during the survey, we used the 1230 with Tx power 100mw,50,30,20,15,10..so on. but the actual ap's to be used are 1242. And on the controller if i set the tx power level of the 1242, it follows the values 1=100,2=50,3=25,4-13.. and so on.


Today as I plugged in a converted 1230 ap and set its power level to 3, i noticed, as i feel my eyeballs came out of my eye sockets, that i got a power value of 32mw. (as seen from the cisco ADU). now where did that come from?


Do different ap's provide different power values as well? even if the controller is configured to power level 1, will different ap's transmit power level according to its hardware spex? is it a hardware spex? can it be changed? is it possible for the 1242 to have the same values as the 1230's tx power values?


As i have stated before, we've had site survey ap's (using the 1230) set to transmit at 30mw but on actual deployment this ap was changed to 1242 and its options for power is 100,50,25.. so on. i'd initially set these ap to power level 3 for 25mw, but the actual survey is 30mw. does the 5mw difference have a big effect on the transmit power?


thanks for your reply and anyone who has some great ideas on this!!!





ED CARMODY Sun, 04/06/2008 - 05:12
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the answer to your last question is "somewhat, sure." not sure if this is the issue your having with our client, but in the future you should really, really survey with the AP (and analogous client, if possible) that is intended to be deployed...but you already knew that...

Scott Fella Sun, 04/06/2008 - 06:18
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We have seen that issues before on the 802.11a side and it was an issues with DFS. It is a good idea to use the ap's that you will be installing, but there are times when you can't. There should be no difference between a 1230 and a 1242... you can put them side by side running Autonomous and see that the power value is the same. What you should do is open a TAC case and see if they have a workaround..... a beta code for you to try:)

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