本文選題：擁塞控制 + AQM　； 參考：《華中師范大學(xué)》2014年碩士論文

【摘要】：隨著互聯(lián)網(wǎng)的不斷發(fā)展,新型網(wǎng)絡(luò)應(yīng)用的不斷涌現(xiàn),特別是語(yǔ)音、視頻等多媒體流量的增加,網(wǎng)絡(luò)信息流量呈現(xiàn)爆炸式增長(zhǎng),帶寬資源變得更加緊張,擁塞問(wèn)題更加嚴(yán)重。另一方面,人們對(duì)于網(wǎng)絡(luò)服務(wù)質(zhì)量如傳輸時(shí)延、吞吐量等的要求越來(lái)越高,擁塞的產(chǎn)生嚴(yán)重影響了這些性能。在這種情況下,如何預(yù)防和控制擁塞成為了亟需解決的問(wèn)題,此類(lèi)問(wèn)題也是國(guó)內(nèi)外研究的熱點(diǎn)。 擁塞控制有兩種機(jī)制,一種是基于源端的TCP協(xié)議控制,另一種則是基于中間節(jié)點(diǎn)(路由器)的擁塞控制。路由器不僅能夠有效地監(jiān)控實(shí)時(shí)隊(duì)列的長(zhǎng)度,且能夠?qū)徱暩鱾�(gè)流對(duì)產(chǎn)生擁塞的影響,從而通知該流的源端進(jìn)行調(diào)整。因此,基于中間節(jié)點(diǎn)(路由器)的擁塞控制機(jī)制在解決擁塞問(wèn)題上有著絕對(duì)的優(yōu)勢(shì)。 主動(dòng)隊(duì)列管理(Active Queue Management, AQM)是基于中間節(jié)點(diǎn)的擁塞控制機(jī)制中最突出的一種。本文系統(tǒng)的評(píng)價(jià)了幾種典型的AQM算法,并對(duì)IETF推薦的唯一的AQM候選策略隨機(jī)早期檢測(cè)(Random Early Detection, RED)算法進(jìn)行了著重介紹。RED算法解決了網(wǎng)絡(luò)突發(fā)流量帶來(lái)的問(wèn)題,但是它在算法穩(wěn)定度、以及參數(shù)敏感性方面仍有缺陷,因此得到了國(guó)內(nèi)外廣泛的研究。本文在RED算法的基礎(chǔ)上,提出了一種非線性自適應(yīng)算法(Nonlinear Adaptive Random Early Detection, NLARED),主要有兩點(diǎn)改進(jìn)：第一,在丟包概率的計(jì)算上,利用模糊數(shù)學(xué)隸屬函數(shù)中的偏大型柯西分布來(lái)代替原來(lái)的線性分段函數(shù)。第二,在算法中加入自適應(yīng)調(diào)整Pmax的機(jī)制。用平均隊(duì)列長(zhǎng)度來(lái)反應(yīng)緩沖資源的占用情況,從而判斷擁塞控制指示是否適度,對(duì)于不同的分段,引入不同基準(zhǔn)量來(lái)調(diào)整Pmax,從而使Pmax的調(diào)整更加準(zhǔn)確、及時(shí),同時(shí)避免引入新的靜態(tài)參數(shù)。 NS2仿真實(shí)驗(yàn)證明,NLARED算法能夠有效地適應(yīng)網(wǎng)絡(luò)流量的變化,保持隊(duì)列長(zhǎng)度的穩(wěn)定,并且減小了參數(shù)敏感性。在維持低的丟包率與高吞吐量上有著明顯的提高,性能優(yōu)于RED。
[Abstract]:With the continuous development of the Internet and the emergence of new network applications, especially the increase of multimedia traffic, such as voice and video, the network information traffic is explosively increasing, the bandwidth resources become more tight, and the congestion problem becomes more serious. On the other hand, the network quality of service, such as transmission delay, throughput and so on, is becoming more and more demanding, which is seriously affected by congestion. In this case, how to prevent and control congestion has become a problem that needs to be solved. There are two mechanisms for congestion control, one is based on source TCP protocol, the other is based on intermediate nodes (routers). Routers can not only effectively monitor the length of real-time queues, but also monitor the impact of each flow on congestion, thus notifying the source of the flow to adjust. Therefore, the congestion control mechanism based on intermediate nodes (routers) has an absolute advantage in solving congestion problems. Active queue Management (AQM) is one of the most prominent congestion control mechanisms based on intermediate nodes. In this paper, several typical AQM algorithms are systematically evaluated, and the random early detection (red) algorithm, which is the only candidate AQM algorithm recommended by IETF, is introduced emphatically to solve the problem caused by network burst traffic. However, it still has some defects in the stability of algorithm and parameter sensitivity, so it has been widely studied at home and abroad. Based on red algorithm, a nonlinear Adaptive Random early Detection (NLARED) algorithm is proposed in this paper. There are two main improvements: first, in the calculation of packet loss probability, The partial large Cauchy distribution in membership function of fuzzy mathematics is used to replace the original linear piecewise function. Secondly, the adaptive Pmax adjustment mechanism is added to the algorithm. The average queue length is used to reflect the occupancy of buffer resources, so as to determine whether congestion control indication is appropriate or not. For different segments, different datum is introduced to adjust Pmax, so that the adjustment of Pmax is more accurate and timely. NS2 simulation experiments show that the NLARED algorithm can effectively adapt to the network traffic change, maintain the stability of queue length, and reduce the sensitivity of the parameters. In maintaining low packet loss rate and high throughput, the performance is better than red.
【學(xué)位授予單位】：華中師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TP393.06

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 羅萬(wàn)明,林闖,閻保平;TCP/IP擁塞控制研究[J];計(jì)算機(jī)學(xué)報(bào);2001年01期

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本文編號(hào)：2058204