RRM confusion

Peter Nugent · ‎05-20-2010

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.

Rob Huffman · ‎05-21-2010

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.

http://www.cisco.com/en/US/products/ps6087/products_tech_note09186a0080736123.shtml

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;

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008072c759.shtml#tpca

Hope this helps!

Rob

Peter Nugent · ‎05-21-2010

Rob

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 · ‎05-21-2010

Hi Pete,

Thanks for your feedback on this +5 points for this

kind follow-up as well as the Troubleshooting tips.

Cheers!

Rob

Peter Nugent · ‎05-21-2010

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 · ‎08-09-2010

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

Thank you

Vic