Command of the Day

Aruba Employee

COTD: Viewing Radio Power- "show ap debug driver-log"

Note: AOS 3.x
The radio driver itself is set with a country code before the radios are turned on. All equipment vendors do it like this. Unfortunately, the code that limits the power and channels is buried in the driver and this makes it difficult to display this information.
Back in 2.5.X, we had power levels specified from 0 to 4. This was not a lot of granularity and power level 0 was really low, this was not good, but it was simple. So in 3.X, we implemented a new feature to set the power in dBm and with finer granularity. The power values in the cli/webUI are now the desired EIRP in dBm. This power setting is expected to be the transmitted power over the air (EIRP) and depend on antenna gain, cables loss, etc. The drawback of this is we do not calculate the regulatory power limits in the user interface, but the driver still clips the transmitted power to stay within regulation limits. Regulation rules are complex, they sometime limits the actual tx power (out of the radio) and sometime EIRP (out of the antenna) which makes it a very difficult thing to show in the GUI.
In short, just remember that the GUI setting is the requested EIRP. If we need to limit this due to regulations, it will be done automatically in the driver in the AP.
There is a "hidden" report from the radio driver that list the actual power settings:
(Greig) #show ap debug driver-log ap-name m1 | include Tx …
14 0.12933 wifi0: Tx Power 0dBm, Actual EIRP 4dBm, Max EIRP 5dBm, TPC Red 1
33 0.52933 wifi1: Tx Power 11dBm, Actual EIRP 12dBm, Max EIRP 27dBm, TPC Red 15
That's it for now.
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