Tim,
First and foremost, if you have WCS, then have a look at the event log and it will have the detailed information on why the AP's are changing channels. Also, WCS, Monitor, RRM will provide an overview of why AP's are changing. Based on my experience, here are a few idea. 1) Upgrade to the latest 6.x code - Cisco has been tweaking their RRM code over the past several releases, and the 6.x seems to have taken a step in the right direction. Specifically, the older code could get in a kind of domino situation where a particular AP may be subject to lots of channel changes, and it would in turn cause cascade channel changes to others. The 6.x code appears to have resolved this. The 6.x code also has some significant radio code improvements. 2) DCA - make absolutely sure that you've not added channels to your selected Country/DCA that were not there to begin with. For example, if you're using US2 (excludes UNII-2 channels), and then add the UNII-2 channels back in, RRM will get very confused, often leading to bizarre and continuous channel changes. Best to select the DCA that has everything e.g. US, then turn off the channels you don't want. 3) Multiple Controllers - RF network name - Connectivity - If you have multiple controllers and they are set with the same RF network name, make sure that there are no connectivity issues between them. If there are problems, the RF group can fragment and the split/join will cause the controllers to go back into RRM startup mode (10 iterations, 10 minutes apart, high sensitivity). This can also happen, for example, when you have a controller in a lab, with no network connectivity to your production controllers, but with the same RF network name. If the AP's can see each other, there is a chance the RF group with try to split/join. 4) RRM - DCA - settings - On the controller (why WCS doesn't have this is beyond me), set the DCA Channel Sensitivity to either Medium or Low, and the Interval to 1 hour or longer depending on your environment. If the APs are deployed in residential halls, 6 or 12 hours may work best. I have 400 APs in a fairly dense deployment, and by following the above, I average about 6 channel changes a day. Jeff >>> Timothy Payne 01/25/10 7:17 AM >>> Good morning! Last year, we were seeing a lot of APs flopping up and down as they changed channels or power levels (per the consultant) for no reason. At that time, we upgraded to 5.2.148.0 and the issues mostly went away, and the ones that remained we were able to work around and planned to replace those APs in our next budget cycle. Our consultant indicated that there are still some issues with this with the new code and old APs. Today, we ran a report of all the 'down/up' events for all the APs and we had around 350 over the last 12 hours. We have around 200 APs, so that average seems to be high. That leads to two questions: 1) Does anyone know of a way to make the report indicated WHY it went 'down/up'? 2) How many times do you see your APs changing channels? My thought is that dynamically they should be changing all the time as load and interference change, but I can't find any documentation to address that. Thanks! Tim Payne, CISSP, CISM, CCNA Network Administrator Macalester College ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
