一种基于卫星网络的虚拟网络功能快速映射算法

Virtual Network Function Fast Mapping Algorithm over Satellite Network

针对卫星网络中卫星载重有限,不允许大规模部署物理硬件,导致其网络功能欠缺且网络管理和配置不灵活的问题,文中提出了基于软件定义网络(Software Defined Networking,SDN)/网络功能虚拟化(Network Function Virtualization,NFV)协同部署的卫星网络新架构。它通过SDN数控分离思想对网络进行动态管控,利用NFV技术在SDN的数字平面虚拟出网络功能,使网络功能能够从硬件设备中解耦出来,从而提高网络的灵活性。为了解决此框架中虚拟网络功能(Virtual Network Function,VNF)映射到底层物理网络上的时延过大且无法满足高动态卫星网络实时性的问题,进一步提出了Viterbi和图形模式匹配(Graph Pattern Matching,GPM)相结合的动态映射方法(Viterbi and GPM Dynamic Placement Approach,VG-DPA)。该算法将映射过程建模为隐马尔可夫服务链,采用Viterbi算法预计算满足软硬件限制的映射路径,然后根据预计算结果通过GPM来制定VNF编排策略。该算法解决了卫星网络中将所需的VNF映射到底层物理网络中时延过大的问题。实验结果表明,VG-DPA与传统的RAND和OMD算法相比能在很大程度上降低时延,减少资源消耗。

A new satellite network architecture based on SDN(Software Defined Networking)/NFV(Network Function Virtualization)co-deployment was proposed to solve the problem that the satellite network has limited load and does not allow the large-scale deployment of physical hardware,which lead to the lack of network functions and flexible network management and configuration.It carries out dynamic control of the network through the idea of SDN data layer and control layer separation,and uses NFV technology to create network functions in the data plane of SDN,so that network functions can be decoupled from hardware devices.In this way,network flexibility can be effectively improved.In order to solve the problems that the VNF(virtual network function)in this framework maps to the underlying physical network with excessive delay and cannot meet the real-time perfor-ance of the high dynamic satellite network,a dynamic mapping method named VG-DPA(Viterbi and GPM Dynamic Placement Approach)based on Viterbi and GPM(graph pattern matching)was further proposed.This algorithm first models the mapping process as a hidden Markov service chain through the estimator,and then uses Viterbi algorithm to obtain the mapping path that meets all the hardware and software constraints.Then,based on the estimator results,VNF scheduling strategy is developed by means of GPM.This algorithm solves the problem of mapping the required VNF to the underlying physical network in the highly dynamic satellite network with excessive time delay.Simulation results show that VG-DPA can greatly reduce the time delay and resource consumption compared with the traditional RAND and OMD algorithms.