Cost-aware Placement and Chaining of Service Function Chain with VNF Instance Sharing

Network Function Virtualization (NFV) is an important shift in telecommunication service provisioning. It enables the decoupling of network element functions and dedicated hardware devices. How to economically place and chain Virtual Network Functions (VNFs) according to the requirements of Service Functions Chains (SFCs) are the challenges for NFV orchestration. In this paper, we consider the offline deployment issue from the perspective of sharing VNF instance to improve resource utilization and reduce total placement costs. Firstly, we generalize the problem as a Facility Location Problem and propose a Mixed Integer Linear Programming (MILP) model. Besides, our model can be dynamically configured according to the different deployment preferences. Then we propose a heuristic algorithm based on the Steiner Tree Problem and Markov Decision Process (MDP). We evaluate our heuristic algorithm by comparing with the optimal solution of MILP and a classic graph based algorithm. The results show that the difference of the deployment costs between our algorithm and the optimal solution is less than 3%. However, the execution time can be significantly reduced by 57.4%.