Same SSID with different WLC in the same building

[reylite]

hello,

so i have a question, in the building we broadcast same SSID but with different WLC, the SSID using dot1x with different ISE too, the problem is some user having difficulty to join SSID, while others having an issue randomly disconnect.

• some AP's join on WLC 5500 series with ISE 2.3
• some AP's join on WLC 9800 series with ISE 2.7

need help to solve this problem

thank you

[patoberli]

Is there a reason that you run the same SSID with different ISE servers? That completely breaks the roaming functionality! I guess this is the issue you see here.

Also, do you have the mobility-group correctly configured between the two WLC (this requires an IRCM image on the 5500 series)? First version for 5500 series supporting that feature:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn85mr6_ircm.html

Can you isolate the join issues to one of the two WLC/ISE combinations?

[reylite]

at first we planned to move all AP's from old controller to the new one but we only bought 20 AP's license so not all AP's can migrate to new one. then we decide to run 2 controller simultaneously without changing configuration on the 5500 series, i didnt configured mobility group, do i need to upgrade to 8.5 first ? because right now my 5500 have 8.3.143 version

[Leo Laohoo]

Client experience got to be horrible.  There is no guarantee people on the 1st floor will associate to the AP found on the 1st floor.  

And when people roam from one floor to another, their session breaks.  

This is a terrible design.

[Scott Fella · Accepted solution]

I’m going to add to what patoberli and Leo has already mentioned. You should plan out and really understand how the technology works. The one thing you do not want is users having a bad experience or else you will never hear the end of it. “It’s a network issue” or “the wireless sucks”. Reach out to the forums earlier in your planning so you get an idea of what you should do and the risk.
The main thing everyone here learns first is mobility and following the compatibility matrix. Roaming is dependent on this. Also running two or more instances of ISE is okay, but only for testing. When you have proven your design, you cut over to the version you want.
Your setup right now will not work. You are better off like mentioned earlier, that you at least upgrade to a version that supports mobility between the two and then pick one version of ISE.

[flabiolq]

Hi, i have same arquitecture, in this moment, i am desing a WLC C9800 new and i have a WLC C5500 operating, i going to have the two WLC work at the same time

Will this cause problems on the network?

[Leo Laohoo]

Yes.  
If the clients do inter-controller roaming there will be issues where their wireless sessions will drop out and re-authenticate again.