本文選題：P2P + DHT��； 參考：《北京郵電大學》2014年碩士論文

【摘要】：隨著網(wǎng)絡(luò)規(guī)模的擴大和用戶數(shù)量的急劇增加,使得互聯(lián)網(wǎng)的流量急劇增加,給網(wǎng)絡(luò)的帶寬造成極大的壓力,也加大了服務(wù)器的負擔,導致服務(wù)不穩(wěn)定。當前C/S架構(gòu)網(wǎng)絡(luò)將信息的傳輸中轉(zhuǎn)和處理都集中在中心服務(wù)器上,容易造成網(wǎng)絡(luò)擁塞和性能瓶頸。于此同時,個人計算機的飛速發(fā)展,使得每臺計算機相比過去都具有較強的計算和存儲能力,而這些性能在大部分情況下沒有得到充分的利用。在這種背景下產(chǎn)生了P2P技術(shù),網(wǎng)絡(luò)中各節(jié)點相互平等獨立,沒有中央服務(wù)器,節(jié)點與節(jié)點之間直接進行信息和數(shù)據(jù)的傳輸。一方面將中心服務(wù)器上的任務(wù)分散到網(wǎng)絡(luò)中的各個節(jié)點,極大的降低了服務(wù)器的和網(wǎng)絡(luò)帶寬的壓力,同時由于P2P的節(jié)點分布特性,使其具有很強的健壯性和可擴展性,避免了單點失效；另一方面也使得個人計算機中未被發(fā)掘的性能得到更充分的利用。 由于沒有中心服務(wù)器,資源分布在網(wǎng)絡(luò)內(nèi)各個節(jié)點中,所以在P2P網(wǎng)絡(luò)中,最關(guān)鍵的問題就是如何找到快速找到存儲資源的節(jié)點。第一代的P2P系統(tǒng)為基于目錄服務(wù)器的架構(gòu),雖然資源都存儲在節(jié)點上,但是需要通過目錄服務(wù)器記錄特定的資源的存放位置,節(jié)點需要先與目錄服務(wù)器通信,得到文件在網(wǎng)絡(luò)上的存儲信息,最后才能與節(jié)點直接通信獲得資源,在用戶增多時,目錄服務(wù)器同樣也會存在瓶頸問題。第二代是非結(jié)構(gòu)化的架構(gòu),采用泛洪的方式在網(wǎng)絡(luò)中查詢文件的存儲位置,在網(wǎng)絡(luò)規(guī)模變大時,會給網(wǎng)絡(luò)帶來較大的負擔,而且查找效率較低。針對以上系統(tǒng)的問題,提出了第三代基于DHT的P2P網(wǎng)絡(luò)。DHT將文件的索引信息存在各個節(jié)點上,取代了目錄服務(wù)器,然后每個節(jié)點利用自身保存的路由信息,通過特定的路由算法就可以快速找到文件的索引信息,最后直接與存儲著文件的節(jié)點進行通信,目前應(yīng)用比較廣泛的是Kademlia、Chord、Pastry、CAN等算法。 目前基于Kademlia的DHT網(wǎng)絡(luò)還存在許多問題和需要改進的地方。首先是基于Kademlia的DHT實現(xiàn)中還沒有基于IPv6網(wǎng)絡(luò)的,無法在純IPv6環(huán)境下使用DHT功能。其次是DHT中節(jié)點的邏輯位置和物理位置完全脫離,使得路由查找時效率不夠高。還有就是當前DHT的架構(gòu)中,由于各個節(jié)點完全平等,節(jié)點經(jīng)常從其他網(wǎng)絡(luò)尋找資源造成過多的跨域流量。針對以上問題通過對Libtorrent函數(shù)庫進行改造,針對IPv6網(wǎng)絡(luò)進行修改,同時融合IPv6的特性,將物理位置信息融入到節(jié)點之中。通過對DHT進行層次化優(yōu)化,使得DHT網(wǎng)絡(luò)具有更好的路由效率。最后利用以上改進,設(shè)計并實現(xiàn)了一個IPv6環(huán)境下基于DHT的P2P媒體分享系統(tǒng),檢驗優(yōu)化方案的效果。
[Abstract]:With the expansion of the network scale and the sharp increase of the number of users, the traffic of the Internet increases rapidly, which puts great pressure on the bandwidth of the network, increases the burden of the server, and leads to the instability of the service. The current C / S network concentrates the transmission and processing of information on the central server, which can easily lead to network congestion and performance bottlenecks. At the same time, with the rapid development of personal computers, each computer has stronger computing and storage capacity than in the past, and these properties are not fully utilized in most cases. In this context, P2P technology has emerged. Each node in the network is equal and independent, and there is no central server, and the information and data are transmitted directly between the nodes. On the one hand, the task on the central server is distributed to the nodes in the network, which greatly reduces the pressure of the server and the network bandwidth. At the same time, because of the distribution of P2P nodes, it has a strong robustness and scalability. The single-point failure is avoided; on the other hand, the undiscovered performance of personal computer is more fully utilized. Since there is no central server and the resources are distributed among the nodes in the network, the most important problem in P2P network is how to find the node of storage resource quickly. The first generation of P2P system is based on directory server architecture. Although the resources are stored on the node, it is necessary to record the location of the specific resources through the directory server, and the node needs to communicate with the directory server first. Only when the file is stored on the network can it communicate directly with the node to obtain the resource. When the number of users increases, the directory server will also have a bottleneck problem. The second generation is an unstructured architecture. When the network scale becomes larger, it will bring a great burden to the network, and the search efficiency will be low by using flooding method to query the storage location of the files in the network. In order to solve the above problems, the third generation P2P network based on DHT is proposed to store the index information of the file on each node, replacing the directory server, and then each node uses the routing information saved by itself. The index information of files can be found quickly by a specific routing algorithm, and finally it can communicate directly with the nodes that store the files. At present, the algorithms such as Kademlia Chorden Pastrycan and so on are widely used. At present, the DHT network based on Kademlia still has many problems and needs to be improved. First of all, there is no IPv6 network in the DHT implementation based on Kademlia, so it is impossible to use DHT in pure IPv6 environment. Secondly, the logical and physical positions of nodes in DHT are completely detached, which makes the routing lookup inefficient. In the current DHT architecture, due to the equality of all nodes, nodes often seek resources from other networks, resulting in excessive cross-domain traffic. In view of the above problems, the Libtorrent function library is modified, the IPv6 network is modified, and the characteristics of IPv6 are fused, and the physical position information is integrated into the nodes. Through hierarchical optimization of DHT, DHT network has better routing efficiency. Finally, a P2P media sharing system based on DHT under IPv6 environment is designed and implemented by using the above improvements, and the effect of the optimized scheme is tested.
【學位授予單位】：北京郵電大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TP393.02

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