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標題: 改進的隨機早期偵測(RED)壅塞控制演算法
An Improved Random Early Detection (RED) Algorithm for Congestion Control
作者: 林偉正 
Lin, Wei-Chung 
關鍵字: Random Early Detection;隨機早期偵測;RED;congestion control;packet loss-rate, Router;壅塞控制;路由器
出版社: 資訊科學系所
引用: [1]V. Jacobson, “Congestion Avoidance and Control,” In Proceedings of SIGGCOMM’ 88 (Stanford, CA, Aug. 1988), ACM. [2] S. Floyd and V. Jacobson, “Random Early Detection Gateways for Congestion Avoidance, ” IEEEE/ACM Transactions on Networking, Vol. 1, pp. 397-413, 1993. [3]湯德佑,駱嘉偉,張大方 “參數自適應的隨機早期檢測演算法,” 系統仿真學報,Vol.15, pp. 1741-1744, Dec. 2003. [4]安智平 , 張德運 , 黨紅梅 ,丁會寧, “一種改進的隨機早期檢測演算法,” 西安交通大學學報, Vol. 37, No. 8, Aug. 2003 [5] H.-C. Lee and F. F. Young, “Congestion Scheme Investigations on TCP/IP Networks,” Department of Electronic Engineering Feng Chia University, Taiwan, pp. 1-8, 2003. [6] S. Flod and T. Henderson, “The NewReno modification to TCPs Fast Recovery Algorithm,” RFC-2582, Apr. 1999. [7] K. Ramakrishnam, S. Floy, and D. Black, “The Addition of Explicit Congestion Notification(ECN) to IP,” RFC-3168, Sept. 2001. [8] W.-C. Feng, D. D.Kandlur, D. Saha, and K. G. Shin, “A Self-Confirming RED Gateway,” IEEEE/ACM Transactions on Networking,pp. 1320-1328, 1999. [9]李磊,潘勇,施鴻寶 “一種分階段自適應RED/ECN 參數模型,”同濟大學計算技術研究所 上海 Vol. 38 , No. 07, 2003. [10]ns-2(Network simulator version 2), [11]柯志亨、程榮祥、謝錫堃、黃文祥 計算機網路實驗-以ns-2模擬工具實作 學貫行銷股份有限公司, 2006.
對路由器的壅塞控制問題,從先前採用的Drop-tail到目前普遍採用的隨機早期偵測(Random Early Detection, RED)演算法,皆為讓網路的封包丟棄機率、產量、公平性等效能有所改善提升,也期望無論是從那一種應用Telnet、FTP、WEB、P2P、VoIP、MOD、e-mail及其它多媒體的資料流封包,路由器在運作壅塞控制機制時也都能有公平性的處理方式。
RED 演算法是為TCP flow設計的ㄧ個主動式佇列管理機制,能在ㄧ定的程度上舒緩網路壅塞,在RED算法中封包丟棄機率與封包的大小之間是相互獨立的,這就造成了對小封包的貶視,使得小封包在網路中的丟棄率較高且產量低的問題。
本文中使用ns-2模擬程式進行實驗,將RED算法、改良過的RED算法RED_average及進ㄧ步改良過後的算法PS_average,三種演算法分成三組MTU(Maximum Transfer Unit)進行比較實驗,分析其所產生的封包丟棄率及產量。

Many proposals have been adopted in controlling the congestions in the routers, including Random Early Detection (RED) and Drop-tail, and have shown to improve the loss rate, throughput, fairness, etc. of the network.
Although RED algorithm is designed for TCP for a active queue management, we found that when comes to dropping the packets, it treats packets equally, ignoring the effect of the the size of the packets. This results in higher loss rate of packets and lower throughput for smaller packets.
In this thesis, we propose to improve the original RED algorithm by differentiating packet sizes and devise RED_average algorithm and further improved PS_average algorithm. We then use ns-2 to simulate the performance of the aforementioned three algorithm.based on three MTU sizes. The results showed that if we take the factor of the packet size into consideration, the RED_average algorithm has a better loss rate and throughput. The PS_average, which takes the average packet size into consideration to adjust the intended loss rate for smaller packates, has a even further improved performance. We have shown that by the above two new algorithms, a better balance for the loss rate for all packets can be achieved, and thus improved utilization of the network resources.
其他識別: U0005-0102200708255200
Appears in Collections:資訊科學與工程學系所

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