Abstract: Concerning the network service failure caused by the virtual network function failure of the service function chain in the network function virtualization environment, a resource utility maximization backup method of virtual network function was put forward to improve the network reliability. First, the backup problem of virtual network functions was analyzed in detail and a reliability evaluation model was established; then a corresponding backup mechanism was put forward, and the advantages of the proposed mechanism over other mechanisms were proved. Secondly, a global backup method and a backup selection strategy were designed to select the corresponding virtual network functions until the reliability requirement was satisfied. Finally, simulation and experimental results showed that compared with GREP, JP+random selection and DSP+random selection, the proposed method achieved excellent performance in terms of reliability and resource utilization, especially improved the rate of request acceptance by 18.8%-25% and the resource utilization ratio by 15%-20%. The experimental results demonstrate that the proposed method can effectively utilize the resources to improve the network reliability.

Key words: network function virtualization, service function chain, virtual network function, reliability, backup

摘要： 针对网络功能虚拟化环境下组成服务功能链的虚拟网络功能故障所引起的网络服务故障问题，提出一种最大化资源效用的虚拟服务功能备份方法来提高网络可靠性。首先，对虚拟服务功能备份问题进行详细分析并建立了可靠性评估模型，提出了改进的备份机制，并证明了该机制与其他机制相比的优势；其次，对全网络设计了全局备份算法和备份选择策略来对相应的虚拟网络功能选取备份直到满足可靠性需求。仿真实验结果表明，与GREP方法、联合备份机制加上随机选择策略（JP+random selection）及双重共享式备份机制加上随机选择策略（DSP+random selection）相比，该方法在可靠性和资源利用率上取得了优异的性能，特别是服务功能链请求接受率提高18.8%~25%，资源效用利用率提高15%~20%。实验结果表明该方法能较为有效地利用资源来提升网络可靠性。

关键词: 网络功能虚拟化, 服务功能链, 虚拟服务功能, 可靠性, 备份