基于启发式调度的OpenFlow网络规则一致更新方案

针对OpenFlow网络在状态转换过程中会暂时性出现转发回路、路由黑洞和违反访问控制策略等问题，提出了一种基于启发式调度的规则一致更新方案.首先，设计基于谓词的更新分解算法，利用并行网络属性验证技术得到子更新依赖图；其次，采用任务图生成算法对子更新依赖图进行分割，降低更新调度的复杂度；之后，设计启发式更新调度算法，采用规则增删操作交替执行策略，减少交换机的规则存储开销，并通过建立更新实施和监听并发执行机制，提升更新效率.仿真实验从更新时间开销和更新过程中交换机规则存储开销两方面验证了方案的有效性.

Consistent Rule Update Scheme Based on Heuristic Scheduling for OpenFlow Networks

In view of such problems as temporary loops,blackholes,violations of access control policy and so on during state transitions in OpenFlow networks,we proposed a consistent rule update scheme based on heuristic scheduling.First,we divided operations of an update into some sub-updates and used parallel network property verification technique to construct a dependency graph for each sub-update.Second,we aggregated several update operations of the same sub-update to reduce complexity of scheduling.Then,we designed heuristic update scheduling algorithm.By adopting an alternative strategy for additions and deletions of rules,it could reduce storage cost in switches.Furthermore,by establishing a mechanism to update and monitor concurrently,it could improve efficiency of rule update.Simulation experiments on the updating time cost and the rule storage cost of switches during updating process are conducted,which verify the effectiveness of our scheme.