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標題: | 設計與實作基於軟體定義網路與服務品質考量之網路位址轉換 Design and Implement an SDN-based QoS Aware Network Address Translation |
作者: | Tsung-Yun Cheng 鄭淙勻 |
指導教授: | 廖婉君(Wanjiun Liao) |
關鍵字: | 網路位址轉換,軟體定義式網路,服務品質,樹梅派, Network address translation,NAT444,Software defined network,Quality of Service,Raspberry Pi, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 網路位址轉換 (NAT) 是當今網路架構中最常見的中間元件之一。以網際網路服務供應商為例,他們通常會在其內部網路中採用NAT444架構來減輕IPv4網路位址耗盡問題。但是,由於網路位址轉換會將封包表頭資訊偽裝,並將由使用者端裝置發送的所有資料流混雜在一起,因此將導致網路營運者很難辨識出每條資料流,也很難對其網路有完整且全面的控制能力。不僅如此,此種技術也會產生許多其他問題,例如規模性、可靠性與打破網路終端對終端原則等等。
因此,我們利用軟體定義式網路 (SDN) 技術來實作網路位址轉換,以達到更細微的管控。藉由將傳統的網路位址轉換硬體替換為支援OpenFlow協議的交換器並統一接受中央控制器的控管,網路管理者將擁有網路的全局資訊,能做到以資料流為基礎的網路行為管理。在本論文中,我們設計且實作出以SDN為基礎的網路位址轉換,並將其實作在樹梅派 (Raspberry Pi) 上作為一個初始模型。此外,我們進一步利用OpenFlow協議支援的隊列模組,在以SDN為基礎的NAT架構網路下,做到以資料流為基礎的服務品質加強。我們以效用函數與傳輸速率來估測每筆資料流的使用者體驗,並將其規劃成一組最佳化問題,於考量公平性因素的同時計算出得到最佳使用者體驗的頻寬分配方式。實驗結果顯示我們的實作能夠以SDN實現NAT的功能,並做到以資料流為基礎的設定,進而達成服務品質加強。 Network address translation (NAT) is one of the most commonly used middle-boxes in the network architectures nowadays. Take the Internet Service Providers (ISP) as an instance, they usually adopt the NAT444 architecture in their internal network to mitigate the IPv4 exhaustion problem. However, since NAT middle-boxes will masquerade the packet header information and mix-up all network traffic flows originating from user devices, the network operators could hardly identify the origin of the data flows or have an overall and complete control of their internal network. Moreover, such a technology also raises a variety of issues such as scalability, reliability, and breaking the end-to-end principle. Therefore, we utilize Software Defined Network (SDN) to implement the NAT function to achieve a more fine-grained control. By replacing the traditional NAT hardware with the OpenFlow switches and making them centrally controlled by the SDN controller, the network operators could have a global network view to manage the network behavior in a flow-based manner. In our work, we design and implement the SDN-based NAT architecture on a low-cost Raspberry Pi platform as a prototype. In addition, we exploit the queue module supported in the OpenFlow protocol to implement a flow-level QoS (Quality of Service) enforcement scheme in the SDN-based NAT. We use utility functions to measure the quality of experience of data flows with respect to the received data rate, and model the bandwidth allocation problem as an optimization problem to derive a solution with optimal utility scores while considering the fairness criterion. Experiment results show that our implementation could achieve the function of NAT and could do flow-level configuration to perform the QoS enforcement. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76440 |
DOI: | 10.6342/NTU201702463 |
全文授權: | 同意授權(全球公開) |
電子全文公開日期: | 2022-09-04 |
顯示於系所單位: | 電機工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
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ntu-106-R00921031-1.pdf | 2.79 MB | Adobe PDF | 檢視/開啟 |
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