Rogue Devices in Unleashed

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I was wondering if I could get some clarification on the RSSI values reported in the rogue devices tab in Unleashed.  The numbers reported are positive values, but the units are dBm.  I am looking at a network that is currently showing a rogue with an RSSI of 40 dBm.  This would mean that the received signal strength is 10,000 mW.  Is this actually the SNR of the received signal, in which case the units would be dB?  Or should these values in fact be negative, in which case the received signal strength would be .0001 mW?  

I need to know which rogue devices are actually being received with stronger signals so that I know which I should try to avoid when channeling my APs.

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Ben Winslow

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Posted 2 months ago

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Albert Pierson, Employee

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Hi Ben,

There is a lot of confusion on labeling of signal level data and what is seen on GUI.

Internally Ruckus Access Points get RSSI values from the radio chip.  This is a pseudo value of 1 to 100 representing the power level detected for the transmission over the noise floor setting.  It is most synonymous to SNR and should be a positive integer in dB (pure ratio).  If you go to the AP CLI (you need to use ap-mode on unleashed master) and do get station wlan(x) show  stats - this will show signal levels in RSSI that are best thought of as SNR (and on dB).

The Access Points do calculate a signal level by adding the RSSI from the radio to the Noise Floor value.  This is reported to the controller which is labeled as RSSI as well - but is really a true signal level in dBm and should be negative.  I have discussed this with Ruckus developers as it is confusing.  Both values are displayed in Ruckus controllers, with the AP RSSI as SNR (dB) and calculated signal level as RSSI (dBm and usually a - number)... I suggested a different name for this later value.

I am not sure what value is being reported for Rogue detection in unleashed - my system did not show any values.  I checked both my ZD and unleashed and neither showed values I could verify (sorry)

I suspect it is the AP RSSI - which is really SNR in dB

You can get a full listing of detected rogues by logging into the master AP CLI (not ap-mode) and go to en; debug;  and run wlaninfo -R  ... this may give better values.

I hope this is somewhat helpful .. I will keep looking into this.

Thanks for your understanding and thanks for choosing Ruckus Networks.

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Ben Winslow

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Thank you for the explanation Albert.  I am unable to attach a screenshot unfortunately, but I think what you are saying is that I am looking at the AP RSSI, which in the WIPS > Rogue Devices section, shows a different value for each AP that detects the rogue.  

So either way, the reported value (whether it be the pseudo-value of 1-100, or the SNR) would be a stronger signal the higher the value.  

You mention 
The Access Points do calculate a signal level by adding the RSSI from the radio to the Noise Floor value.  This is reported to the controller which is labeled as RSSI as well - but is really a true signal level in dBm and should be negative.
Is this displayed in the GUI, and is just missing the negative sign, or is this only used internally for calculations?  Because the numbers I am seeing are labelled dBm, and are in the RSSI column.  If these are that value, and should actually be negative, the smaller numbers would indicate a stronger signal, as they would be closer to zero.

I understand I can probably get clearer information from the CLI, however, the GUI is a bit more convenient.

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Albert Pierson, Employee

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I just figured out why I did not see values on my unleashed or ZD - did not hit the + button showing the AP's detecting the signal (oops).

From the values I am seeing I am sure this is really AP RSSI - ie SNR and is in dB not dBm ... the values are a positive integer as this this is a pure ratio.  Near by AP's show higher numbers and distant AP's lower - which would not make sense if this was an absolute power level just missing the -

I will see if I can get some traction in Ruckus engineering to fix the GUI.

Thanks