SDN网络虚拟化中规则映射研究

软件定义网络（SDN）为网络虚拟化提供了新的解决方案，通过网络虚拟化技术可以将一套基础设施虚拟化为多个逻辑网络从而满足不同的网络需求.本文研究了SDN网络虚拟化时多个物理交换机虚拟为一个大虚拟交换机的过程中，虚拟网络规则与物理网络规则的映射问题.综合考虑链路负载、规则分布以及节点负载，提出了三段式规则映射优化算法.首先根据虚拟网络的规则请求生成组播源节点和目的节点集，采用MPH算法生成规则映射树；然后采用入节点最近原则，将虚拟网络规则请求的指令序列部署到规则映射树中的中间节点和叶子节点中；最后考虑节点负载，对规则部署进行微调，最终生成虚拟规则映射策略.通过仿真实验，与直接边缘节点部署相比，平均降低了网络节点规则总数量40%以上.

Research of Rule Mapping on Network Virtualization in SDN

Software Defined Network (SDN) provides a new solution for network virtualization, which can virtualize a set of infrastructures to multiple logical networks to meet different network requirements. This paper studies the mapping of virtual network rules to physical network rules when multiple physical switches are virtualized into one big switch in SDN network virtualization. Considering link load, rule distribution and node load, this paper proposes a three-stage rule mapping optimization algorithm. First, according to the rules of the virtual network, the multicast source node and a destination node set are located, and a rule mapping tree is generated by using the MPH algorithm. Then, the rules of the virtual network rules are deployed to multiple nodes of the physical network. Finally, with the consideration of the node load, the rule deployment is finely-tuned to generate the virtual rule mapping strategy. Simulation results show that compared with direct egress node deployment the average number of network node rules is reduced by more than 40%.