Annoying wireless router

[Jason Shein]

On April 28, 2005 10:31 pm, Steven Nagy wrote:

> I had problems with it meaning that the router does not transmit signal
> every time. I changed it back and I got another router having the same
> problem.
>
> But as I saw, the guy gave me another router from the left side of the
> shelves and it was not sealed. I didn't have problems for maybe a week. But
> today the same problem occurred and the router is not transmitting
> continuously.
>
> I analyzed the signal with a wireless access point analyzer program called
> Network Stumbler and I got the following results:
>
>
>
> http://www.stevenscreations.info/Download/MyRouter.jpg
>
> This was a very bad situation. Now the signal returned back with short
> interruptions about every minute.
>
Wireless. My specialty :)
Hopefully this can be of some assistance to you. 

Step 1: Kismet

Kismet is your friend. Learn to use kismet. Seeing as you are using a windows 
based program, then you might want to consider getting a knoppix cd to do 
this. kismet is a passive sniffer and will detect many more AP's ( 2-3x ) 
than network stumbler. 

The reason is that there are only 3 non-overlapping channels on the b/g band.

1    6    11

Thats it. If someone else is running near your location on a channel that is 
the same or a channel that is close to yours, ( ie 6 & 4 ) it can cause 
interference. This MAY cause drop-outs, bandwidth reduction. Try different 
channels to see if that changes the behavior. Also check your SSID for your 
AP. if you have not changed it ( ie "default" or "linksys" ) and your 
neighbor has done the same, then you could be hopping between AP's. Stranger 
things have happened. I once had a client who lived in an area where 5 
neighbors within a 1000 foot circle all had default linksys routers running 
on the default channel 6 and a SSID of LINKSYS. Strange phantom computers, 
shares and printers kept appearing, then disappearing, and the connection was 
inconsistent.

Step 2: wavemon

Once connected to the AP, start up wavemon and see how the actual signal 
quality is. Look for the number of errors.


Step 3: Hardware misbehaving

I have run into certain combinations of PCMCIA cards and access points that 
have had personality differences. Simply by changing the card or the AP the 
probelm was fixed.

Step 4: Interference

Some things can cause strange interference with wireless. I heard of one 
instance where the wireless AP would for no reason drop the client. Random 
times, random length of time etc. it turned out that it was the neighbors 
microwave oven that was causing the drop every time it was used ( Wonder how 
THAT passed radio interference inspection )



-- 
Jason Shein
Director of Networking, Operations and Systems
Detached Networks
jason-xgs8i/e9EeWTtA8H5PvdGCwD8/FfD2ys at public.gmane.org
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( 905 ) - 876 - 5817 Mobile
http://www.detachednetworks.ca
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