Reliable service function chain provisioning in software-defined networking

A Service Function Chain (SFC) is an ordered Network Function (NF) chain to process flows or packets for the end-to-end delivery of network services. In the context of Network Function Virtualization (NFV) and Software-Defined Networking, which are promising technologies for next generation networks, the Virtualized Network Function (VNF) can be deployed on either generic physical machines or virtual machines. A challenging problem is to determine where and how to place these VNFs of an SFC request in the network. In this paper, we first formulate this VNFs placement problem as an Integer Linear Programing (ILP) model and then propose an enhanced VNF placing scheme based on layered graphs to achieve better reliability. To improve the reliability, our scheme avoids placing more than one VNF of an SFC on the same node to protect the SFC from a single point of failure. We have conducted a numerical analysis and computer simulation for the feasibility validation of our scheme. The performance results, in terms of end to end delay of SFC and computation time cost on different topologies, show that our scheme performs well in different scenarios.