The paradigm shift in network control is envisioned as the next evolution milestone of mobile communications. A more flexible control of network technologies will be enabled by implementing the concept of Software Defined Networking (SDN). This dictates that amongst others users' mobility in mobile networks should also be managed by SDN controller. In this paper, we develop necessary tools and software modules to realize the SDNized WLAN. We then implement a distributed mobility management protocol and investigate its performance in terms of handover delays. The paper focuses on studying the delay sources and the impact of system dynamics (e.g., topology size and controller load) on different delay components. To carryout investigations in a more realistic environment, we develop a full scale SDN controlled WLAN testbed.