近些年，隨著網路技術地不斷進步、行動網路及物聯網技術的發展，網路直播、影音串流等應用使得網路流量與日俱增，為了保障網路通訊的可靠及安全性，我們需要通過有效的網路監控，為網路故障的定位以及惡意流量的偵測提供資料。軟體定義網路(Software Defined Networks, SDN)為網路監控提供了一個彈性的平台，其依靠集中控制器與交換機連線來獲得全局流量視野。然而，在軟體定義網路中可用來做網路監控的資源是有限的，如交換機的效能，在網路監控任務日益增多的情況下，會影響數據平面流量傳輸的效能。為解決這一問題，本論文提出了一個讓網路監控任務能均衡地分配給各節點(交換機)的網路監控框架FlowSpy，並使用P4(Programming Protocol-Independent Packet Processors)語言更加靈活地定義數據平面封包處理管道，能相對減少數據平面與控制平面的頻繁互動對網路品質的影響，相比基於OpenFlow的軟體定義網路架構為監控提供了更多的彈性，讓每台交換機充分發揮其監控能力，相較傳統監控方法能完成更多的監控任務並且没有節點超過其負荷。

With the rapid development of network technology and growing services running, there is more network traffic on the Internet. To ensure the reliability and security of network, we need to do more effective network monitoring tasks that can help us gain more information for network troubleshooting and malicious traffic detection. Software-Defined Networks (or SDN, for short) provides a flexible platform for the network monitoring and relies on a central controller and switches interact with each other to gain a global view of traffic. However, the capacity of network monitoring are limited in SDN, such as switch performance. Thus, too many monitoring tasks will affect data plane traffic performance. To address this issue, we proposed FlowSpy which is a load balancing network monitoring framework using P4 (Programming Protocol-Independent Packet Processors) programming language in SDN. P4 program can specify how a switch processes packets, that can reduce the overhead of the interaction between data plane and control plane in SDN, and provides more flexibility for monitoring than OpenFlow-based SDN. As compared to existing network monitoring methods, FlowSpy can take more monitoring capacity at each switch for complete more monitoring tasks without any overloaded nodes.

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