Nowadays,  Software-Defined Networking (SDN) is a powerful architectural model,
decoupling control and forwarding planes through
the abstraction of network elements and functionalities.
As known, in SDN networks the controller is the key element since the intelligence of the network is centralized. Hence, the deployment of network services, such as QoS, traffic engineering and traffic recovery, requires the design and development of control apps.
In this paper we focus on load balancing and traffic recovery, specifying a controller architecture and integrating the above-mentioned services on top of the POX platform. Moreover, different levels of protection are implemented depending on the QoS guarantees required by the flow (on per class-of-service basis).
To validate the behaviour of our controller, we considered a network with fat-tree topology, widely deployed in modern data centers: after the functional assessment, load balancing performance have been compared for different traffic flows and cost assignment strategies.