近一年來受到廣大矚目與迴響的軟體定義網路(SDN)， 顛覆網路長久以來的架構和思維， 改變傳統網路架構的控制模式，從分散式走向集中控管架構，網路設備趨於標準與簡單化，而以軟體為主的控制器(Controller)躍升為網路管理與控制的主角， 大幅提升網路運作的彈性與效能， 降低營運與管理成本， 必將成為下一代網路技術發展的重心。本文針對開放網路基金會(ONF)提出的SDN架構與運作模式、實現SDN架構的OpenFlow通訊協定、協調整體網路運作的SDN Controller 基本功能和開放源碼(Open Source)計畫分析比較、以及結合SDN特性的內容傳輸服務技術作一介紹。

For the past one year, Software Defined Networking (SDN) has drawn much attent ion and exploration. It overturned the long-existent concept and architectural principle of traditional networking as distributed to become concentrated control and management. As a result, networking device was largely standardized and simplified; it stages the software-based Controller to play the main role in network management and control, enhancing to a great extent the flexibility and effectiveness in the operation of network. The article introduces what is proposed by ONF on the architecture and operation of SDN, OpenFlow protocol, SDN Controller functions and comparison of Open Source Controller projects, and SDN-enabled content delivery service technology.