基于VNF实例共享的服务功能链部署算法

针对服务功能链(SFC)部署过程中存在虚拟网络功能(VNF)实例部署成本和转发路径成本难以权衡的问题，提出了基于VNF实例共享的SFC部署算法。首先针对多链SFC建立VNF和虚拟链路映射模型，并预估路径部署长度上限，保证SFC时延需求；其次，在路径部署长度限制范围内，尽可能使VNF实例共享最大化，以平衡链路转发成本和VNF部署成本，最终得到SFC部署策略。与已有的SPH(shortest path heuristic)和GUS(greedy on used server)部署算法相比，所提算法所得的总运营成本分别降低6.6%和12.15%,且当SFC数量增多时，该算法的服务接受率可达89.33%。仿真实验结果表明，提出算法可以在保证用户服务质量的同时有效降低SFC部署成本。

Service function chain placement algorithm based on VNF instance sharing

This paper proposed an SFC(service function chaining) placement algorithm based on VNF(virtual network function) instance sharing to address the problem of difficult tradeoff between the deployment cost of VNF instances and forwarding cost in the process of SFC placement. Firstly, for multi-link SFC, it constructed the VNF and virtual link mapping model, and estimated the upper bound of the path deployment length to ensure the SFC delay. Secondly, within the limit of the path length, it maximized the number of the reused VNF instance as much as possible to balance the forwarding cost and the deployment cost of VNF. Finally it obtained the SFC placement strategy. Compared with the existing SPH(shortest path heuristic) and GUS(greedy on used server) placement algorithms, the total operating expense of the proposed algorithm is 6.6% and 12.15% lower, and when the number of SFC increases, the service acceptance rate of this algorithm can reach 89.33%. The simulation experimental results show that this algorithm can effectively reduce the SFC placement cost while ensuring the quality of service.