基于分类搜索的SDN流表无环一致性更新方案

在软件定义网络(Soft ware-Defined Networking,SDN)中,由于配置策略的改变导致控制器需要对多个交换机中的流表项进行更新时,会出现更新不一致的情况.其内在原因是控制器无法同时对所有交换机完成更新,不同的更新时延会导致网络状态在逻辑上的不一致,从而影响数据报文的正确转发.针对分类时序更新方案应用场景适用性差和更新时延长,最优化更新方案计算复杂度高等问题,本文在两者的基础上,提出基于分类搜索的无环更新一致性方案(Categorical Search based loop-free Consistent Update scheme,CSCU).方案通过设计交换机分类模型,并在分类的基础上,结合节点依赖思想设计环路搜索优化模型,实现更新时延短,更新效率高的一致性更新.仿真结果表明,本方案有更好的场景适用性和更低的节点操作复杂度,也有更少的更新轮次和更低的计算复杂度,可有效提升更新性能.

Categorical Search Based Loop-Free Consistent Update Scheme for Flow Tables in SDN

In Software-Defined Networking (SDN), inconsistent updates are frequent when the controller needs to update the flow table entries in multiple switches due to the change of configuration policy. The internal reason of this phenomenon is that the controller updates all switches asynchronously. Update delay leads to the logical inconsistency of the network state, affecting the correct forwarding of data messages. With regard to poor generality of application scenarios and prolonged update time of the classification and sequence based update scheme and high computational complexity of the optimal update scheme, this study proposes a Categorical Search based loop-free Consistent Update scheme (CSCU) for flow tables. In this scheme, a switch classification model is developed on the basis of classification, and a loop search optimization model is built according to the idea of node dependence. Those contributions achieve the consistent update with short update delay and high update efficiency. The simulation results show that the proposed scheme has promising applicability with lower node operation complexity as well as fewer update rounds, which can markedly improve the update performance in terms of lower computational complexity.