Replace 5520 standby unit

[tiwang]

hi out there

I have a 5520 WLC running 8.10.something with SSO enabled. I have to replace the standby-unit - is there a way to awoid interrupting operations? As far as I can see the suggested way is to disable SSO - which will cause both devices to reboot -> our global wlc will be down for a pretty long periode...

Is not not possibly to load the current config of the standby device on the new stnadby unit - fysically switch the device of and replace?

[balaji.bandi]

You do not need to config all the information for the failed unit - check below thead to replace RMA unit.

https://community.cisco.com/t5/wireless/wlc-5508-replace-primary-unit-in-ha-pair/m-p/3094412

[tiwang]

Yes i have seen that but my goal is to avoid interruption of the traffic. This will force a reboot of both wlc's as i read it - i need a way to avoid interruptions 

[Rich R · Accepted solution]

I don't think any interruption is needed.  Turn off secondary.  Install and configure new secondary exactly as old one, same firmware and software as old one.  When you enable SSO it should reboot and sync to primary.
https://www.cisco.com/c/en/us/support/docs/interfaces-modules/wireless-services-module-2-wism2/117729-configure-wlan-00.html#anc7

"Replace the Primary WLC in HA Setup

The primary WLC was affected and the user must replace it. The secondary WLC is up and all APs are attached to it. The new WLC received return material authorization (RMA) can be added with one of the failed WLCs in the HA pair. Follow the steps in this section in order to understand how to replace a WLC in active setup.

1. Make sure that the first WLC is the same version as the other WLC.
2. Configure the WLC with the same subnet management IP addresses as the previous WLC.
3. Configure the new WLC with HA configuration that includes redundant management, IP address, and peer primary. Enable the AP SSO.
4. When the AP SSO is enabled, it reboots. While it reboots, the AP SSO discovers the current active secondary, syncs the configuration, and transitions to a hot standby state.

Note: You do not need to break the HA configuration on the current active WLC or reboot the current active WLC. The configuration will be synced with the current active WLC."

Same as that but secondary.

https://community.cisco.com/t5/wireless/replacing-8510-wlc-in-an-ha-pair-environment/td-p/3076933