Although the openflow-based software defined network (SDN) architecture can ease the workload of network control and management and separate it from the switch/routing operations, a computation-resource limited controller can still be congested by heavy flows and then experiences serious delay. To enhance network scalability and reduce computation delay on SDN networks under Quality of Service (QoS) requirements, a hierarchical edge-cloud SDN (HECSDN) controller system design is proposed with three features. First, by sharing computational resources in the edge and the cloud, the system architecture provides a flexible mechanism for devices to allocate their computational tasks according to traffic loads. The second feature is to design a queueing model of the proposed architecture. The model description of the networking architecture enables the network designers to quickly estimate the performance of design without considerable time and cost in experimental setups. Third, derived from the queueing model, an efficient load-balancing algorithm satisfying QoS requirements or fairness allocation for different applications in the HECSDN architecture is proposed. This newly-developed multi-tier controller system has been proved to be effective even when working on a large-scale SDN, without sacrificing the overall performance. Moreover, this system stays highly stable in transient periods even under highly fluctuating flow arrivals.

中文翻译：

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具有优化的自适应资源分配能力的分层Edge-Cloud SDN控制器系统

尽管基于开放流的软件定义网络（SDN）架构可以减轻网络控制和管理的工作量，并将其与交换/路由操作分开，但是计算资源有限的控制器仍然会因繁琐的流量而变得拥塞，从而遭受严重的延迟。为了在服务质量（QoS）要求下增强SDN网络的可扩展性并减少SDN网络上的计算延迟，提出了具有三个功能的分层边缘云SDN（HECSDN）控制器系统设计。首先，通过在边缘和云中共享计算资源，系统体系结构为设备提供了一种灵活的机制，可根据流量负载分配其计算任务。第二个特征是设计所提出体系结构的排队模型。网络体系结构的模型描述使网络设计人员能够快速估算设计性能，而无需花费大量时间和金钱来进行实验设置。第三，从排队模型出发，提出了一种满足QoS要求或公平分配的高效负载均衡算法，用于HECSDN架构。实践证明，这种新开发的多层控制器系统即使在大型SDN上工作时也有效，而不会牺牲整体性能。此外，即使在流量波动很大的情况下，该系统在瞬态期间也能保持高度稳定。提出了一种满足QoS要求或公平分配的HECSDN架构中不同应用的高效负载均衡算法。事实证明，即使在大型SDN上工作时，这种新开发的多层控制器系统也是有效的，而且不会影响整体性能。此外，即使在流量波动很大的情况下，该系统在瞬态期间也能保持高度稳定。提出了一种满足QoS要求或公平分配的HECSDN架构中不同应用的高效负载均衡算法。实践证明，这种新开发的多层控制器系统即使在大型SDN上工作时也有效，而不会牺牲整体性能。此外，即使在流量波动很大的情况下，该系统在瞬态期间也能保持高度稳定。