网络服务功能链技术研究与建模

伴随着数据业务量的急剧增长，传统的静态网络服务模型日渐不能满足应用的需求，其构架中网络服务与专用硬件设备之间一一对应的紧耦合关系造成了网络资源不能共享、新业务难以融合等弊端。当网络规模扩大时，传统的管理和部署方式需要投入更多的成本来部署新业务。随着网络虚拟化的兴起与软件定义网络研究的推进，网络服务功能链这一概念应运而生。网络服务功能链由一个或多个虚拟网络功能组成，旨在降低网络建设与运维成本、提高网络资源利用率、提升网络与业务部署速度。针对当前服务功能链体系的研究及建模和应用进行了阐述，并对业内主流的服务功能链优化模型进行抽象建模。同时针对时延优化问题进行仿真，以启发式贪婪算法为代表，通过不同的启发值，从算法时间复杂度与优化效果的角度将服务功能链中启发式算法与穷举法进行对比。在网格状网络的环境下，启发式算法能取得更快的响应速度，并且能取得和穷举法相当的优化效果。因此，得出在大规模工业互联网中部署服务功能链过程中启发式算法能有更快的响应速度，且能达到或者接近最优解的结论。最后，就当前建模与部署存在的问题以及服务功能链未来的研究方向进行论述。

Survey and modeling on network service function chain technology

With the rapid growth of traffic data, the traditional static network service model is increasingly unable to meet the needs of the applications. In traditional network architecture, it tightly coupled the relationship between service and dedicated hardware devices, which results in the drawbacks of network resources could not share and new network business was difficult to integrate. As the network continues to expand, traditional management and deployment requires more cost to deploy new services. With the rising of network virtualization and the development of software defined network, the concept of service function chain has come into being. A service function chain is composed of one or more virtual network functions to provide a complete end-to-end service for the network. The service function chain aimed to reduce the cost of network construction and operation and improve the utilization of network resources and improve the speed of network and service deployment. This paper elaborated the current service function chain system research and its application in industry. It summarized the development and application of service function chain. This paper put forward a heuristic greedy algorithm with two different heuristic values. And compared the exhaustive method in the time complexity and results of delay optimization. In the result, it figured out that the heuristic greedy algorithm is more suitable for industrial network. Finally, this paper discussed the modeling and drawback of service function chain present in present.