This is a confusing algorithm. Basically, think of it this way: 1) Three neighbors (at least) hear an APs radio at or stronger than the TPC Tx mac value configured under the WLC TPC settings for that PHY (802.11a/n or 802.11/b/g/n) 2) If #1 is true, then that formula provided is used. - The "Tx_Max for given AP" is the maximum transmit power for that channel on that particular radio. So, for a 2.4GHz radio, that would be 100mW (20 dBm), since that is the maximum for 802.11b. 5GHz is more confusing, as it various based on channel and model of AP. - The "Tx power control thresh" is the value that is entered in the WLC - Note that there is an "hysteresis" value of 3dB for decreasing and 6dB (or it was at one point - someone correct me for the current values) for increasing the power levels. In other words, the value that is given at the end of the formula has to be at least that dB difference from the current value in order for a change to occur. 3) The AP's radio that is heard by the other three APs is the one that is decreased (or it can be increased) if the hysteresis value is exceeded. 4) When the formula is run again, it is presumed that the three neighbors that are hearing the APs signal are hearing a weaker signal. 5) Keep in mind that the algorithm is always from the perspective of an AP being heard by 3 or more neighbors, not an AP hearing 3 or more neighbors.
Hope this helps. Jason Boyers, CCIE #26024 (Wireless) Blog: netboyers.wordpress.com On Wed, Sep 11, 2013 at 9:36 AM, Jeen Sern Chew <[email protected]> wrote: > Hey guys, > > I have a TPC question. > > There are many conflicting information from different Cisco docs. Some say > TPC increase and decrease power, some say TPC only decreases power while > CHD increases power. Does TPC do both or only increase? > > Also Cisco gives the TPC formula of: > Tx_Max for given AP + (Tx power control thresh – RSSI of 3rd highest > neighbor above the threshold). > > Is the Tx_Max is the Tx_Max of the specific AP? or Is it the Tx_Max > configured on under TPC in WLC? > > Also, when the calculation is done, I am assuming the power > increase/decrease occurs on the neighbour with the third highest RSSI? > > Thanks > > Regards, > J Chew > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > >
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