Notes on how to upgrade to 7.6+ from 7.4 for use by the general public.

WLC Upgrade process to 7.6 from 7.4 with AP Predownload and FUS for a pair of 5508s
Scenario: There are 2 WLCs, WLC1 and WLC2. For this scenario, we assume that this is a N+N, and that both WLCs have clients on them. This scenario is how to perform the upgrade to 7.6 including the FUS 1.9 upgrade with minimual downtime.
*It is suggested that you have a PC with a serial cable (not USB) connected to the WLC during the FUS upgrade. If something happens during the FUS upgrade, it is benefitial to be able to tell TAC where in the process it died.

  1. Turn off Fallback on both WLCs and save configs on both WLCs. (Controller > General > AP Fallback)
  2. Check to make sure at least one of the following is configured:
    1. All APs have a Primary and Secondary controller configured
    2. Both WLC1 and WLC2 are in the same Mobility Group
  3. Upgrade FUS on WLC1
  4. Reboot WLC1, APs should failover to WLC2 and stay put. Expect this process to take 45 minutes to 1 hour
  5. Once WLC1 returns from the FUS, perform the upgrade to 7.6.x
  6. Reboot WLC1
  7. Perform code upgrade on WLC2 to 7.6.x (NOT FUS)
  8. Once upgrade is complete, from the CLI issue the command "config ap image predownload primary all"
  9. Occassionally run "show ap image sum" until all APs have completed the predownload process
  10. Once all APs are predownloaded, Reboot WLC2
  11. Once WLC2 has rebooted, perform FUS Upgrade on WLC2.
  12. Once WLC2 has booted back up, enable Fallback on both WLCs.
  13. APs should now move back to their primary controller.