Network Functions Virtualization (NFV) enables the rapid development, flexible management, and the dynamic placement of new, innovative Virtualized Network Functions (VNFs), such as load balancers, firewalls, and Intrusion Detection Systems (IDSes). Furthermore, NFV along with Software-Defined Networking (SDN) allows VNFs and physical middleboxes to be dynamically composed into service chaining graphs. Despite these benefits, service chaining graphs can be further improved through the use of techniques that have not been satisfactorily explored yet, such as Policy-Based Network Management (PBNM). In PBNM, policies can be written and triggered during runtime, thus supporting the dynamic (re)configuration of service graphs with minimal disruption. In this paper, we propose an approach to automatically design NFV service chaining graphs based on policies. These policies rule the forwarding of traffic and the construction of service chaining graphs. In our approach, service chaining graphs are enforced dynamically in the network during runtime. Finally, to assess its feasibility and generality, we create two different scenarios to demonstrate and discuss how our solution can be employed and its expected results.
