透過OpenFlow支援的多網路裝置以提高應用程式效能

Abstract

在這個科技蓬勃發展的時代，無線網路正以飛快速度成長，尤其在複雜的行動裝置和客戶端應用程式方面更有明顯的增長，這些裝置都配備多種網路介面，如Wi-Fi、3G、4G LTE，但同時僅能使用一種介面，所以在面對頻寬和時間較敏感的即時多媒體應用時，常常會帶給使用者負面的經驗。因此在這篇論文中，我們嘗試在可靠的網路連接下，同時使用多種介面，這使得應用程式能夠把流量分配至多種介面上，並且能夠聚集不同路徑的總容量，如此不僅適應於不同網路環境中，並且增加應用程式的頻寬效能。為了達成這個目標會面臨一些技術上的挑戰，因為傳統設備的作業系統並不允許同時使用多種介面。利用OpenFlow彈性的特性，我們提出了一個客戶端的雛型系統稱為OpenMWF (OpenFlow-based Multiple WLAN Interface) ，它將OpenFlow控制器與Open vSwitch嵌入在客戶端的裝置上，如此能夠允許上層的應用程式同時存取多個無線區域網路的介面達到多工的目的。在使用案例中，我們擴充了目前現有的視訊會議軟體（WebRTC）和多來源下載軟體（Aria2c）來支援此設計，並且實際地在應用程式上進行測試與評估，結果顯示多種介面之使用表現優於單一介面的使用。

This age of technology is witnessing phenomenal growth in wireless networks, which ushered in an exponential increase in sophisticated multihomed devices and client applications. These devices are equipped with multiple network interfaces such as Wi-Fi, 3G, 4G LTE, but restricted to using one single interface at a time. The demand for bandwidth and latency sensitive real time media applications is also overwhelming. As a consequence, the devices cannot satisfactorily meet the performance requirements our client applications. In this thesis, we advocate for the use of multiple interfaces simultaneously, which can achieve reliable network connectivity, allow applications to distribute their traffic over multiple interfaces, aggregate different paths capacity, so as to improve the performance of applications. However, some technical challenges due to the network stack of the legacy devices operating system which does not allow using more than one interface at a time need to be tackled. We deployed the rich features of OpenFlow to present a client prototype called OpenFlow-based Multiple WLAN Interface (OpenMWF) that enables multiple interfaces access. We designed the OpenMWF by embedding OpenFlow resource controller (NOX) and a data forwarding Open vSwitch (OVS) in the network stack of the device operating system. Finally we carried out an extensive evaluation of the system using Web-based Real-Time Communication (WebRTC) interactive video conferencing and multi-source downloading utility (Aria2c) applications.