臺灣博碩士論文加值系統

虛擬通道會合可以將多個虛擬通道會合，再經由同一個虛擬通道輸出。這麼做可減少虛擬通道辨識碼的使用數目，增加系統在管理虛擬通道辨識碼時效率。虛擬通道會合時，所有來自要會合但不同虛擬通道的細胞們，將被標上相同的虛擬通道辨識碼，再傳送至下一個ATM交換機。如何辨識這些有相同虛擬通道辨識碼的細胞，這將是下一個接收到這些細胞的ATM交換機所遇到的問題。有幾種方法被提出來解決這個問題。然而，這些方法有的需要大量的緩衝器，有的會有較長的時間延遲，有的更需改變ATM交換機的軟體及硬體設計。在本篇論文中，吾人提出了一個方法來解決虛擬通道會合時衍生的問題。使用此方法不需要動到ATM交換機原本的硬體架構，只需在軟體方面作調整。吾人將此法和其他已被提出的方法，於相同的測試環境條件下，利用計算機來模擬比較系統性能表現。實驗結果顯現出，吾人提出的方法，有較低的封包遺失率，有較高的系統產出量，平均封包延遲時間也不差。

VC-merging allows many Virtual Circuits (VC) to be merged to one output VC. The number of Virtual Circuit Identifiers (VCI) is reduced when VC-merging is performed. The performance efficiency for managing the VCIs can be improved. When VCs are merged, all cells from different VCs will be tagged with the same output VCI and sent to the next ATM switch. This switch will face a problem, that is how to identify these cells belonging to different packets of different VCs? Various methods have been proposed to solve this problem. However, these methods may need a large amount of buffers, have very long packet delay time, and need to change the hardware of the ATM switch. In this paper, we propose a method to solve the problems caused by VC-merging in ATM network. With this method, the hardware of the ATM switch needn’t to be changed. However, the modification of software is needed. We use a simulation program to analyze the performance of these methods. The results show that the method proposed has lower packet loss rate, better throughput, and acceptable average packet delay.

中文摘要 ---------------------------------------------I
英文摘要 ---------------------------------------------II
圖表索引---------------------------------------------V
第一章緒論 ----------------------------------------1
1.1研究動機 ---------------------------1
1.2 研究簡介 ---------------------------1
第二章背景知識與相關研究 --------------------------4
2.1非同步傳輸模式 ---------------------4
2.2IP switching ----------------------10
2.2.1IP和ATM的結合 -------------10
2.2.2資料流的分類 --------------11
2.2.3IP交換機動作原理 ----------12
2.3Tag switching -------------17
2.3.1Tag switching的動作原理 ---17
2.3.2標記交換機 ----------------19
2.3.3標記配置法 ----------------20
2.4IP switching和Tag switching的比較 --22
2.5IP switching和Tag switching的限制 --24
2.5.1IP switching的限制 --------24
2.5.2Tag switching的限制 -------26
第三章虛擬通道會合的方法 --------------------------29
3.1何謂虛擬通道會合 -------------------29
3.2虛擬通道會合方法介紹 ---------------30
第四章虛擬通道會合效能之模擬分析 ------------------39
4.1模擬模型與參數 ---------------------40
4.2緩衝器工作模式 ---------------------45
4.3實驗結果 ---------------------------46
4.3.1三種虛擬通道會合方法的比較 -46
4.3.2共用式緩衝器和獨立式緩衝器的比較 -66
4.3.3細胞丟棄式和封包丟棄式的比較 -----67
第五章結論 ----------------------------------------69
參考文獻 ---------------------------------------------71

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