This message indicates that a client has left the AP coverage area and has reassociated to a different Access Point (AP). It is not necessary to perform additional troubleshooting when clients roam. However, if the APs are connected to switches, multicast must be permitted between those switchports. If you have more than one AP in your wireless LAN, wireless client devices can roam seamlessly from one AP to another. The roaming functionality is based on signal quality, not proximity. When a client's signal quality drops, it roams to another AP.
Wireless LAN users are sometimes concerned when a client device stays associated to a distant AP instead of roaming to a closer AP. However, if a client's signal to a distant AP remains strong and the signal quality is high, the client will not roam to a closer AP. Checking constantly for closer APs would be inefficient, and the extra radio traffic would slow throughput on the wireless LAN.
IOS Errors, Warnings, Statistics and Log Messages
DOT11-6-ROAMED: Station [mac-address] Roamed to [mac-address]