- 學位論文
點對點內容遞送網路與內容分享 虛擬計價之研究
Research on Peer-to-Peer Content Delivery Network and Virtual Pricing for Content Sharing
摘要
點對點內容分享網路服務讓大眾可以透過網際網路有效且快速的獲得所需的多媒體內容，因此點對點內容分享網路的需求有高度的成長。然而使用者下載多分享少的自私行為已造成點對點內容遞送網路健康成長所必須面對的嚴重問題。本論文研究的主題是改善點對點網路中權利義務不平均的搭便車問題(Free Riding Problem)。 在點對點內容分享網路中的搭便車問題分成兩個層次，第一個層次是使用者對於內容的搭便車，第二個層次是使用者對於傳輸服務的搭便車。為了改善或甚至消除這種權利與義務不均的問題，本研究採用一個兩階段式的策略:(1)使用者登錄內容遞送服務網路時必須提供一些檔案分享； (2) 使用者在虛擬計價的市場機制下使用代幣交換檔案與服務。為了實現這兩個策略，本研究在網路架構上設計一個結合混合式(hybrid)與超節點模式(super peer)的點對點內容分享網路架構並將之命名為超節點混和式點對點內容分享網路（簡稱 SPH PPCDN）。SPH PPCDN特色一是採用超節點可靠的特性，把搜尋功能交給超節點執行:特色二是採用混和式方便管理的優點，把會員管理交由中央會計伺服器處理。在策略搭配上，當使用者登錄超節點時，由超節點執行第一階段的策略；當使用者執行搜尋時同樣由超節點執行第二階段的策略。為了分析使用者對於兩階段策略的反應，在階段一的部分，考慮了當使用者提供檔案以加入SPH PPCDN時的受益函數與成本函數，藉此效益函數可作為判斷使用者該提供多少內容的函數模型以及對於整體網路的效益。在階段二的部分，考慮使用者傳輸服務的提供與使用，建立使用者的傳輸服務效益模型，作為虛擬計價時內容價格決定的基礎。 最後，本論文實作一個省略中央會計伺服器的超節點混合式點對點網路環境}，實現具有登錄時使用者提供內容數量門檻的點對點檔案分享網路。在SPH PPCDN中，以Visual basic.NET整合搜尋與檔案傳送功能後，在超節點上加入階段一的內容數量門檻策略機制。本研究的實作設計省略中央會計伺服器，階段二機制之實作有待未來研究。
並列摘要
People can easily download various multimedia contents using peer-to-peer content delivery service over the Internet. In spite of the increase in needs for peer-to-peer content sharing, selfish user behavior of free riding, i.e., significantly more content downloads and service usage than content uploads and service provision, have had negative impact on the healthy growth of a Peer to Peer Content Delivery Network (PPCDN). The research of this thesis focuses on resolving the free riding problem for the growth of PPCDNs. There are two aspects of free riding on a PPCDN. One is free riding on content, and the other is free riding on delivery service. In order to improve or even eliminate the free riding phenomena, a two-stage policy is adopted. At stage 1, users have to provide their contents for sharing when they log in a PPCDN. At stage 2, users trade contents and delivery services over a market with virtual pricing, where super peer checks if users have enough tokens to search or not and price is based on the reputation/ quality statistics of a provider. When users upload/download content to other people, central accounting server get tokens from users/issues tokens to users. To enable the two stages policy, we design a peer to peer network architecture by combining the ideas of super peer and hybrid mode PPCDNs which is named Super Peer Hybrid PPCDN (SPH PPCEN).First feature of SPH PPCDN is that super peer mode is better reliable on search, therefore super peer deal with search request. Second feature of SPH PPCDN is that hybrid mode is better on management, therefore central accounting server deal with management. In the thesis, two-stage policy is adopted in SPH PPCDN, where stage 1 is applied when users log into a super peer and stage 2 is applied when users send search requests to a super peer. To analyze users’response to the two stages strategy, At stage one, we consider user benefit and cost function when user joint SPHPPCDN with provided contents. Based on this utility function , we can analyze how many contents user have to provide and calculate total utility of the whole SPHPPCDN. At stage two, we consider the actual provision and usage of delivery service and establish delivery service utility model being the basis of price determination in virtual pricing. Finally, we implement a simplified SPH PPCDN environment, which realizes the threshold mechanism of content contribution when users logged in PPCDN by Visual basic.NET. Through Visual basic.NET, We integrate the search and content delivery technology, and implement the content number threshold strategy on super peer. Due to eliminate central accounting server on implementation design, the implementation of stage two policy will be the future work.