topic Re: change subnetmask on controller in Wireless

change subnetmask on controller

Hubert Kupper — Mon, 05 Jul 2021 20:06:02 GMT

Hello, I must change the subnetmask on the management interfaces of our controllers, because the IP range in the subnet reaches its limit. Our APs are configured with static IP adresses. Do they fall back to DHCP when I change the mask or must I change every AP to dhcp previous?

Regards, Hubert

Re: change subnetmask on controller

patoberli — Tue, 06 Apr 2021 15:52:35 GMT

Neither should happen. But you should adjust the subnet mask on each AP afterwards for correct broadcast function.

Re: change subnetmask on controller

Scott Fella — Tue, 06 Apr 2021 18:02:55 GMT

Patoberli is right. don't half a$$ it. If you change anything for the management, come up with a plan to make changes to all devices using that subnet. Seems like you are better off using dhcp and remove the static, then once you have everything up and running, then create the static if you want. Mac address reservation I think would be better for you, just think everything through so you don't end up with a bunch of access points that no longer connect.

Re: change subnetmask on controller

Hubert Kupper — Wed, 07 Apr 2021 04:10:19 GMT

The plan was to use dhcp for future instead of static IPs. I thought when change the subnetmask on all controllers and the dhcp server the APs will do a fallback to dhcp and join the controllers after the change. Am I right?

Re: change subnetmask on controller

Scott Fella — Wed, 07 Apr 2021 06:35:49 GMT

The ap's fallback to dhcp when the ap can't discover the controller. I would not count on that as that can cause you issues. Take time and figure out what steps you need to take to reduce downtime.

Re: change subnetmask on controller

patoberli — Wed, 07 Apr 2021 06:42:35 GMT

Yes, in a certain way. Only if the AP can't reach the WLC with the configured IP address it will switch to DHCP. You didn't write anything about changing the AP manager interface, so I expect the AP to not switch to DHCP.
I personally would first switch them all to DHCP (with option 43) and afterwards change the WLC interface configuration.

Re: change subnetmask on controller

Hubert Kupper — Wed, 07 Apr 2021 08:51:41 GMT

Ok. Thanks for the answers. I will figure out a way with the least downtime.