多網路介面之網路管理系統與事件通知機制的設計與實作

Abstract

隨著網路科技的快速發展以及網際網路的盛行，網路生活已成為人們生活中不可缺少的一部分，雲端科技也成為近年來討論的話題，傳統的上網方式已經不能滿足市場上迫切的需求。 随著資訊產品的快速整合，目前許多的設備都已有內建網路介面，有些還同時支援多個介面，如Ethernet、WiFi、3G及WiMAX等等。不過一般在使用這些多介面設備時，同一時間只能使用一個介面上網，不同介面也會有不同的頻寬，當然我們會希望使用WiFi來下載檔案同時，還可以使用3G來瀏覽網頁，如此便可有效的運用網路資源。 目前為止，很少看到有這樣的工具可以設定多個介面同時上網，也因此開發出一個能夠管理多介面的管理系統便成了一件刻不容緩的事情。這樣一個工具需能夠有效結合事件通知機制，事件通知機制主要是讓管理系統可以針對所有網路的行為，如插上網路介面、移除網路介面、斷線或拔掉網路線及時反應，如此才可以讓使用者在很短的時間就可以連到網際網路，或在其中一個介面斷線時盡快切換到另一個介面。 本論文的主要目標在於發展一個多網路介面之網路管理系統與事件通知機制，讓嵌入式網路通訊裝置的開發者可以利用此工具，來快速開發自己的網路工具或讓使用者使用工具，以便管理多個網路介面。 本論文以Linux作業系統平台實作此工具，經由實驗的測試結果並分析相關數據，結果證實本機制確實可以管理多個網路介面，並且比現行Linux上的NetworkManager來得有效率。

With the rapid development of technologies and the popularity of the Internet, network life has become intertwined with people’s lives. Cloud technology has continued to be a topic for discussion in the recent years. The traditional method for Internet access cannot sustain the market demand. Due to the accelerating integration of informational products, many devices now have built-in the network interface capabilities. Some of them even support multiple interfaces, such as Ethernet, WiFi, 3G, WiMAX, etc. However, in general, users can use only one interface at a time to access the Internet even if the device at hand is equipped with multiple interfaces. Furthermore, different interfaces may have different bandwidths or access delays; therefore, they are best suited by specific applications. We hope to fully utilize resources whenever it is deemed necessary. As a result of the interfaces being more suitable for some applications, we can use WiFi, which has high bandwidth, for file downloads and 3G, which has low bandwidth, for internet browsing. Thus far, it has been difficult to find such a tool, but the development of an apparatus to maintain multiple interfaces is great urgency. This tool must be combined with an event signaling mechanism so that applications may adjust their behaviors quickly under various network conditions, such as plugged-in or unplugged network interfaces, plugged-in or unplugged Ethernet cable lines, and so on. Furthermore, this tool also enables users to access the Internet instantly or change interfaces immediately when the original interface malfunctions. The subject of the thesis is to design a multiple interface management system and an event signaling mechanism. This tool can help the developers of built-in networking devices efficiently create communication software and assist the user in managing multiple interfaces. The thesis introduces the design and implementation of this tool on a Linux OS platform. Experimental results show that this tool can indeed manage multiple interfaces efficiently -- even better than the network management software, namely NetworkManager, of Linux.