Application-Centric provisioning of virtual security network functions

Network Function Virtualization (NFV) enables flexible implementation and provisioning of network functions as virtual machines running on commodity servers. Due to the availability of multiple hosting servers, such network functions (also called Virtual Network Functions (VNFs)) can be placed where they are actually needed, dynamically migrated, duplicated, or deleted according to the current network requirements. However, the placement of VNFs within the physical network is one of the main challenges in the NFV domain as it has a critical impact on the performance of the network. In this work we focus on efficient placement of Virtual Security Network Functions (VSNFs), i.e. the placement of virtual network functions whose purpose is to prevent or mitigate network security threats. In this regard, we tackle the placement problem not only considering performance optimization aspects, but also trying to find solutions that are consistent from the security viewpoint. Specifically, the main contribution of this paper is the formulation of the placement problem by taking into account both Security and Quality of Service (QoS) requirements of user applications.