The switched Ethernet networks are more and more deployed in industry. The Spanning Tree Protocol implemented in the switches enables management of the link connectivity. But the reconfiguration time of the Spanning Tree Protocol (STP) when link failure occurs is not adapted to satisfy industrial constraints. The objective of this paper is to propose a method based only on standard, mitigating the probability of disconnection between nodes having hard real-time properties. The approach developed in this paper consists of duplicating frames and of forwarding them on different paths. These paths are optimized and specified by using genetic algorithms. OPNET simulations show the interest of this proposal on a particular Networked Control System.