While virtual networks have been subjected to detailed analysis, prototypes are usually constructed and instantiated manually or by means of control protocols that mostly neglect security considerations. In this work, we present our proposal for a Virtual Link Setup Protocol (VLSP) that is designed as a modular extension to a standardized and extensible state-of-the-art signaling protocol suite. We use these signaling protocols to combine an authenticated and on-demand setup of virtual links with the establishment of Quality-of-Service guarantees in the underlying substrate. The solution presented in this paper is not limited to a specific set of virtualization techniques or tunneling mechanisms. We describe the design and implementation of VLSP and evaluate its signaling performance, as well as the overhead that is associated with the instantiation of the virtual links.