Minimizing the Embedding Cost of Service Function Chains with Adjustable Order

Network Function Virtualization (NFV) has becoming an emerging technology for ensuring the reliability and security of data flows. The virtual network function (VNF) embedding problem, which tries to minimize the embedding cost has attracted extensive interests recently. However, the existing works always assume the fixed execution order of VNFs, which limits their application. Thus, we investigate the VNF embedding problem without such limitations in this paper. Firstly, a general transformation framework is proposed for the NFV-enabled unicast routing with adjustable order. Then, an optimal algorithm is proposed for the unicast VNF embedding without delay constraints. Additionally, an efficient algorithm is also proposed for such problem with delay constraints. Finally, we evaluate the proposed algorithms via numerical results, which show that our algorithms significantly outperform the existing benchmarks.