I got a new controller and I would rather keep the old one up until I finalize the new one. They would have different names but I'm afraid the AP's are going to see the new one and hook into it. Once I do the change all the notebooks have to reset to the new name and right now that is a pain with 2 wireless labs.
You can keep both controller up until you are ready to switch. The AP's will not attach to the new controller until you add the new wlc to the AP's. If you want both controllers running at the same time you need to add both to the same mobility group and create the same WLANs on each controller. Once the new wlc is ready to be used you can add the wlc to all the AP's. When you remove the old wlc all the AP's will move to the new controller. Clients will not have to reconfigure anything as long as you have the same settings on the new wlc.
I created the 2nd controller with the same SSID etc. as the first with the name of the controller with a different name. I shut down the first one, they all moved except one so I bumped the switch off and on and the last one kicked in. The 2 laptops that were on the old SSID controller kicked right into the new one. I did create the same mobility group on both but it didn't seem like it was necessary.
The mobility group is important if you are going to utilize two controllers on the same building. If you have ap split into both controllers mobility helps with the roaming. Mobility group also is used for ap fallback or ap's joining the secondary controller if the primary fails.
I'm just going to use one controller, the other controller is going to another building. I now want to get to NTLM authentication which I understand is available in the latest release. thanks for help with both issues.