RRM confusion

Unanswered Question
May 20th, 2010

I should know this and maybe I am over thinking the issue but I will explain

I have 3 sites and 1 controller.

We are not using H-REAP.

What is the best way to seperate the sites on the controller so each site has its own RRM setup.

I thinks using H-REAP groups is the best however I am getting confused.

The issue I am seeing is all aps are on max power and I am assuming it as it is one large RF domain at present with no segregation it sees the distance between sites as a coverage hole and goes to max power.

I have this problem too.
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Overall Rating: 5 (2 ratings)
rob.huffman Fri, 05/21/2010 - 06:33

Hey Pete,

You are most correct that these H-REAP AP's will not likey  participate in RRM so you will require manual adjustments.

Because of  the fact that many remote deployments have only a small handful of  H-REAPs, full Radio Resource Management (RRM) functionality might not be  supported at each H-REAP site. Full RRM code is present in the H-REAP,  but the Transmit Power Control (TPC) algorithms in RRM are not triggered  until four or more access points are within range of each other. So,  some H-REAP installations might never power their radios down.. As such,  without ever being able to power down their radios in the first place,  H-REAPs do not adjust transmit power upward to compensate in the event  of a coverage hole detection.


Note: The  802.11a Cisco Radio supports five transmit power levels: 1 = Maximum

transmit  power level allowed per Country Code setting, 2 = 50% power, 3 = 25%

power,  4 = 6.25 to 12.5% power, and 5 = 0.195 to 6.25% power.

Each AP  reports an RSSI-ordered list of all neighboring APs. Provided an AP has  three or more neighboring APs, the RF Group Leader applies the TPC  algorithm on a per-band, per-AP basis in order to adjust AP power  transmit levels downward such that the third loudest neighbor AP is  heard at a signal level of -65dBm (default value) or lower.

Power  changes are only made when the third loudest neighbor of a given AP is  heard at a signal level higher than the default value of -65 dBm.

Power Level  Assignment Method-The TPC algorithm can be configured in one of three  ways:

Automatic-This  is the default configuration. When RRM is enabled, the TPC algorithm  runs every ten minutes (600 seconds) and, if necessary, power setting  changes will be made at this interval. ****This is a display-only field  and cannot be modified.****

From this excellent doc;


Hope  this helps!


Peter Nugent Fri, 05/21/2010 - 07:43


Many thanks, been doing some more investigation, tuning the RRM algoritm to -75dBm is recommended as the thinking is that -65 is too hot.

Im OK with the H-REAP however what I have found as the client has MPLS and has not used H-REAP to segregate his areas, which is fine, is that if the PAs cannot here another ap at -85dBm sub groups may form like clusters within the RF group.

My understanding is this building 1 all aps can see neighbouring aps so they form a group, As thenext building cannot see any of these ap at -85dBm they form a subgroup and manage their RF independently of the group in the fist building.

I dont know if there is any visibility of this a my lab wont scale to that! However it makes sense it would just be nice to see.

Oh the source for this is the troubleshooting WLCs book, great read.

rob.huffman Fri, 05/21/2010 - 09:43

Hi Pete,

Thanks for your feedback on this +5 points for this

kind follow-up as well as the Troubleshooting tips.



Peter Nugent Fri, 05/21/2010 - 16:52

Hey Rob

I shouldn't score for answering my own question!

I don't spend as much time here as I would like and the score is appreciated, spending too much time studying etc.

Congrats on the Hall of Fame!

Victor Fabian Mon, 08/09/2010 - 11:47

Have you had any good experience using RRM on your enviroment ?

Thank you



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