Online and Scalable Virtual Network Functions Chain Placement for Emerging 5G Networks

In 5G network slicing, different services can be modeled as a set of Service Function Chains (SFCs), i.e., graphs of interconnected Virtual Network Functions (VNFs), within a specific network slice. The optimal placement of these SFCs is of paramount importance for the network slice performance. Nonetheless, this problem remains partially unresolved, primarily because it requires managing resources distributed across various Edge and Cloud sites in different geographical locations. Moreover, the complexity of the problem significantly increases when considering constraints such as end-to-end delay, processing delay, VNF affinity, and traffic requirements between VNFs. This paper addresses this problem and proposes both offline and online practical solutions for the Virtual Network Functions Chain Placement Problem (VNF-CPP) that are based on Integer Linear Programming (ILP) and heuristic algorithms. Furthermore, theoretical analysis and simulations are provided to verify the efficiency of the proposed placement algorithms.