本篇研究提出了PiSNet測試平台，用於建立真實的SDN（Software-Defined Networking，軟體定義網路）環境，供研究者進行SDN的網路模擬。有別於市面上昂貴的OpenFlow交換器，PiSNet中的基礎設施是由數個低成本、體積小的Raspberry Pi嵌入式電腦所組成。透過控制層與應用層的實作，我們的PiSNet可以做到一般SDN模擬器所擁有的功能，包含網路拓樸使用的彈性以及容易地重製網路實驗。更重要的是，SDN將是未來物聯網成熟的主要關鍵議題之一，假若未來需要在物聯網中部署SDN交換器，PiSNet中所使用的基礎設施將具備良好的可攜帶性，有利於物聯網中網路設備的使用。最後，我們分別在PiSNet以及Mininet上使用TCP與UDP類型的即時影片串流進行端點對端點延遲的量測，發現Mininet對於串流類型流量的效能量測會產生令人誤解的結果，說明了目前被廣泛使用的SDN網路模擬器仍然有其局限性。

Software-Defined Networking (SDN) is a new architecture that has been designed to enable more agile and cost-effective networks. SDN architecture consists of three layers that accessible through open APIs: the infrastructure layer, the control layer, and the application layer. SDN enable simple programmatic control. The separations of the forwarding hardware form the control layer allow easy deployment of new protocols and applications.
In this research, we proposed a SDN network testbed, called Pi Software-Defined Networking (PiSNet), to provide a realistic SDN experiment environment with Raspberry Pi (a low cost PC). The infrastructure layer of PiSNet is constructed with number of Raspberry Pi(s) as forwarding devices. The control layer and the application layer of PiSNet is also implemented to provide advantages such as flexibility of network topology, easy replication of network experiment, and close to real experimental results by network emulator.
To validate the proposed PiSNet testbed, we experiment of TCP and UDP live video streaming applications and compare the results of end-to-end delay and packet loss on PiSNet and Mininet. The results showed that our PiSNet is able to simulated and produced more realistic results compare to the SDN network simulators such as Mininet. We concluded in this research that PiSNet testbed is a portable and a cost-effective solution which provides realistic SDN experiment environment.

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