change the WLC's IP

[robert.huang]

We have a 5508WLC and 12 APs(AIR-LAP1142N-A-K9) deployed in our company. The APs are using static IPs(don't know why previous support person chose this way). WLC and APs are on different subnets. Now we have a task to change the IP of the WLC. Say change from current 10.54.15.88 to 10.64.15.88. I can take care of the layer2 and layer3 setup. The most important thing for me is that after the WLC's IP changing, those APs are still be able to join the WLC.

Here's my plan.

on the WLC, set up the new WLC's IP and name as the primary controller for each AP, then reload the WLC. Since now all the APs have the primary controller's IP configured, once they lose connectivity to the old WLC's IP, they should be able to find the the new WLC's IP and join it.

Please provide any suggestions. I don't want to unmount the APs from the ceiling and console in to configure.

Thanks in advance.

Robert

[Scott Fella · Accepted solution]

Since you only have one WLC, the easiest way is to allow the broadcast.  On the AP vlan layer 3 interface, assign a new ip helper addres pointing to the new ip of the WLC.  Then globally on the l3 switch, configure ip forward-protocol udp 5246.  Then you can rename the WLC and change the ip address and reboot.  After they join you can remove the configuration.

You can also setup option 43 or dns to help the ap's find the wlc.

[robert.huang]

Thank you Scott for your reply. Your suggestion definitely works for DHCP clients.

Just out of curiosity, according to my plan, I manually configure the new WLC's IP as the primary controller for each AP. Will the AP still be able to join the WLC after reloading the WLC?

Robert

[Scott Fella]

I don't think that will work, because part of the AP knowing that infor is from the mobility group info.  You can try, it won't hurt.

[robert.huang]

Thanks Scott.

Just want to confirm with you. As I mentioned in my first post. The APs are using static IP right now. Which mean the APs won't send out DHCP request. I'm afraid the command of "ip helper-address" on the layer3 interface won't work for client using static IP.

[Scott Fella]

It will still work for the clients… I do it all the time☺