I did a test in our lab where I roamed from an AP on WLC A to an AP on WLC B. My client kept its same IP address and connectivity remained. I'm running WLC 4.0.219, so the traffic at this point was not symetrical, but the connectivity was up. WLC A was the Anchor WLC.
Then, I failed WLC A. My wireless client still had its original IP address from WLC, so I lost all connectivity. WLC B did not try to anything so that my client would get a new IP address (from WLC B) and regain connectivity.
The only way I could get my client to work again was to go to WLC B and "Remove" the client. It looks like this forced the client to re-authenticate and get a new IP address.
Is this the only way to get a client back on the network in this type of failure scenario?