發(fā)布時(shí)間：2018-02-02 01:24

  本文關(guān)鍵詞： 網(wǎng)絡(luò)模擬 動(dòng)態(tài)路由 局部路由策略 擁塞預(yù)知　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來互聯(lián)網(wǎng)技術(shù)不斷發(fā)展，信息化進(jìn)程日益推進(jìn)，互聯(lián)網(wǎng)技術(shù)在改善人們生活方式的同時(shí)也帶來了很多問題。一方面，各種網(wǎng)絡(luò)安全問題不斷涌現(xiàn)，信息安全事件時(shí)有發(fā)生；另一方面，網(wǎng)絡(luò)規(guī)模和復(fù)雜性的增長對(duì)現(xiàn)有的協(xié)議和算法提出了更高的要求，亟需研究人員進(jìn)行前瞻性的研究。由于網(wǎng)絡(luò)模擬在研究網(wǎng)絡(luò)行為和網(wǎng)絡(luò)協(xié)議方面具有成本低、靈活性強(qiáng)、模擬規(guī)模大等優(yōu)點(diǎn)，因此，得到了越來越廣泛的應(yīng)用。 在真實(shí)的網(wǎng)絡(luò)環(huán)境中，路由策略的好壞直接影響到一個(gè)網(wǎng)絡(luò)的性能，同樣，在網(wǎng)絡(luò)模擬環(huán)境中，如何模擬數(shù)據(jù)包在真實(shí)網(wǎng)絡(luò)環(huán)境中的轉(zhuǎn)發(fā)過程將直接影響模擬的真實(shí)性和模擬效率。因此，網(wǎng)絡(luò)模擬中路由策略的設(shè)計(jì)至關(guān)重要。 基于上述背景，，本文設(shè)計(jì)并實(shí)現(xiàn)了支持動(dòng)態(tài)路由的網(wǎng)絡(luò)模擬系統(tǒng)，主要完成了如下工作： 第一，研究了當(dāng)前網(wǎng)絡(luò)中廣泛使用的動(dòng)態(tài)路由協(xié)議，分析了各個(gè)協(xié)議的優(yōu)缺點(diǎn)，在NS3上實(shí)現(xiàn)了簡化的OSPF協(xié)議模型，主要包括：鏈路狀態(tài)通告的獲取，鏈路狀態(tài)數(shù)據(jù)庫的構(gòu)建，路由選擇算法SPF的實(shí)現(xiàn)，路由表的生成以及路由的更新過程。 第二，由于網(wǎng)絡(luò)信息量的不斷增加，擁塞已經(jīng)成為制約網(wǎng)絡(luò)性能的主要因素，因特網(wǎng)中廣泛使用的OSPF、RIP、IGRP等路由協(xié)議對(duì)數(shù)據(jù)包進(jìn)行路由時(shí)總是選擇“最優(yōu)路由”進(jìn)行轉(zhuǎn)發(fā)，使得鏈路擁塞時(shí)其它空閑的鏈路無法得到利用，造成大量網(wǎng)絡(luò)資源的浪費(fèi)。針對(duì)這一問題，提出了一種擁塞預(yù)知隊(duì)列模型，通過周期性的檢測(cè)隊(duì)列緩沖區(qū)占用率來判斷鏈路的擁塞狀況，當(dāng)隊(duì)列緩沖區(qū)占用率達(dá)到一定閾值時(shí)，則認(rèn)為鏈路有發(fā)生擁塞的趨勢(shì)。 第三，針對(duì)擁塞問題，提出了一種擁塞預(yù)知路由算法CPRA，算法采用了局部路由策略的思想：當(dāng)隊(duì)列緩沖區(qū)占用率達(dá)到一定閾值時(shí)，通過深度優(yōu)先搜索尋找另一條通往目的節(jié)點(diǎn)的路徑，然后將數(shù)據(jù)包沿著該路徑轉(zhuǎn)發(fā)。在NS3上的仿真結(jié)果表明，相對(duì)于OSPF，使用CPRA能夠顯著提高網(wǎng)絡(luò)的性能，其中，網(wǎng)絡(luò)吞吐率提高了約50%，端到端平均時(shí)延減少了0.3s。
[Abstract]:In recent years, with the continuous development of Internet technology, the process of information technology is advancing day by day. Internet technology not only improves people's way of life, but also brings a lot of problems. On the one hand, a variety of network security problems continue to emerge. Information security incidents occur from time to time; On the other hand, the growth of network size and complexity puts forward higher requirements for existing protocols and algorithms. Because network simulation has the advantages of low cost, strong flexibility and large simulation scale in studying network behavior and network protocol. Has been more and more widely used. In the real network environment, the routing strategy directly affects the performance of a network, similarly, in a network simulation environment. How to simulate the forwarding process of packets in real network environment will directly affect the authenticity and efficiency of simulation. Therefore, the design of routing strategy in network simulation is very important. Based on the above background, a network simulation system supporting dynamic routing is designed and implemented in this paper. The main work is as follows: First, the dynamic routing protocols widely used in the current network are studied, the advantages and disadvantages of each protocol are analyzed, and the simplified OSPF protocol model is implemented on NS3. It mainly includes: the acquisition of link state notification, the construction of link state database, the implementation of routing algorithm SPF, the generation of routing table and the updating process of routing. Secondly, due to the increasing amount of network information, congestion has become the main factor that restricts the network performance. OSPFN RIP, which is widely used in the Internet, is widely used. IGRP and other routing protocols always select the "optimal route" to forward the packets, which makes the other idle links can not be utilized when the link is congested. In order to solve this problem, a congestion prediction queue model is proposed to determine the congestion status of the link by periodically detecting queue buffer occupancy. When queue buffer occupancy reaches a certain threshold, the link is considered to be congested. Thirdly, a congestion predictive routing algorithm, CPRA-based, is proposed, which adopts the idea of local routing strategy: when queue buffer occupancy reaches a certain threshold. Another path to the destination node is found by depth first search, and then the packet is forwarded along the path. The simulation results on NS3 show that it is relative to OSPF. The performance of the network can be significantly improved by using CPRA. The throughput of the network increases by about 50 and the average end-to-end delay decreases by 0.3 s.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TP393.08

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