Coverage Hole Detected

[bobmcbride]

Hello,

I have recently started to get a lot of “Coverage Hole Detected for AP03 whose Base Radio MAC is…….. Number of Failing Clients 1” across my company site, a couple of mins later the trap log reports “Coverage hole cleared for Base Radio MAC……” When the hole is created a client is disconnected from the network causing them problems. I have searched on the Internet, but cannot seem to find a great deal of information on this issue.

We have 2x WLC 4402 (Primary & Secondary) running software version 4.2.130.0 with 24 Access points model AP1020 boot version 2.1.78.0.

There have been no changes recently to the network, no alterations to the building or impact from companies either physically or via RF.

Can anybody provide any answers or point me in the right direction to investigate further.

Kind Regards

[bbxie]

This warning message means that initially the WLC had detected there's a coverage hole in your RF network, then the WLC found it can resolve it by increasing the transmit power of nearby AP. This is one part of Cisco's RRM.

A coverage hole is detected if both the number and percentage of failed clients meet or exceed the values entered in the Min Failed Client Count per AP and Coverage Exception Level per AP fields over a 90-second period. The controller determines if the coverage hole can be corrected and, if appropriate, mitigates the coverage hole by increasing the transmit power level for that specific access point.

If you keep on receiving "Coverage Hole Detected", and there's no "Coverage hole cleared for Base Radio MAC……”, then you have to add more APs in that area, but if after several minutes, you receive "Coverage hole cleared for Base Radio MAC……”, then you don't need to do anything, because Cisco's RRM had resolved it automaticaly.

Pls. see following link for more detail:

http://www.cisco.com/en/US/docs/wireless/controller/5.1/configuration/guide/c51rrm.html#wp1175067