The deployment of wireless networks in critical industrial environments must ensure the availability of monitoring and control applications, for which it is essential to exploit redundancy techniques. In order to reduce to zero the failover time, in this paper, the Parallel Redundancy Protocol (PRP) is used in Wireless Local Area Networks (WLAN) which are implemented under the Software-Defined Networking (SDN) paradigm. It is discussed how the OpenFlow protocol allows an external controller to configure redundant paths between dual-homed devices. As a result, critical services can be protected in interference and mobility situations. The improvement in availability has been obtained by using both emulation and simulation.