Frequency lock problem with WDS

[Joe Parks]

Something is *UP* with WDS.   It is as if the radio is not "locked" on the proper frequency or something.   I can't explain this, and I suspect it is leading to throughput problems.   Give it a try though.  It's quite amazing.

This test demonstrates that radios tuned to and transmitting on different channels are somehow able to communicate with one another despite how improbable that sounds.

Setup:  2 computers with radio cards running hostap driver.   (any version that supports WDS) 

On computer A issue the following commands:

iwconfig wlan0 essid "crosstest"
iwconfig wlan0 mode master 
iwconfig wlan0 channel 6 
iwpriv wlan0 prism2_param 14 1 
iwpriv wlan0 prism2_param 8 1 

Likewise, issue the following commands on computer B:

iwconfig wlan0 essid "crosstest"
iwconfig wlan0 mode master 
iwconfig wlan0 channel 1 
iwpriv wlan0 prism2_param 14 1 
iwpriv wlan0 prism2_param 8 1 

If the computers are sufficiently close together (within a few feet of each other this always works) they will quickly form a WDS connection with one another.

You can see this connection listed with:

cat /proc/net/hostap/wlan0/wds

On each machine an interface wlan0wds0 will now exist that you can bind an IP address to.  

On computer A:
ifconfig wlan0wds0 192.168.6.1

On computer B:
ifconfig wlan0wds0 192.168.6.2

Try some pings. This will confirm that data is actually flowing through this "Cross-Channel" connection.

If you try this test with different channel arrangements you should see that the 'closer' the channels are in frequency to one another, the further apart the computers can be and still establish a working WDS connection.