臺灣博碩士論文加值系統

在網路的傳輸過程中，封包長度的大小與網路傳輸效率一直是個值得研究的議題。若網路負載低且封包的長度採用固定值時，網路傳輸效率還可以接受。但是當網路負載很重時，網路傳輸效率則明顯下降。因為封包長度越大，網路被抓住(hold)的時間越久，發生碰撞的機會較高，因此網路壅塞的情況也就更嚴重，而且一旦發生碰撞後，比較長的封包所需重送時間也就越多。
本研究的主要目的是動態監督網路負載的變動，並且透過一個簡易的換算方程式來動態改變封包的大小，以提高網路的傳輸效率。因此我們的實驗環境分成對照組與測試組。對照組的環境是實際記錄一般網路的使用狀況。實驗結果明顯顯示，在固定封包長度的傳輸方式下，其網路傳輸效率與負載之間呈現負的指數關係。相反地，採用本文所提動態調整封包大小的傳輸方式，整個網路傳輸效率獲得改善，其網路傳輸效率與負載之間，則是負的倒數關係。

The packet size is one important design issue to be used in the network. There is a significant relationship between packet size and transmission time.When the network is not in the heavy load, the packet which contains fixed amount data can be sent efficiently, but it decreases the efficiency when the network is in heavy traffic. This is because it needs more time to recieve an entire packet and it takes a very long time when sends an entire message.If we break up an original packet into two packets, the internet node can begin transmitting first packet as soon as it has arrived from source station , without waiting for the second packet.
The main purpose of this research is to improve the network transmission time. We record the network traffic by Sniffer. Depending on the network traffic situation, a better size of the packet can be obtained automatically by simple calculation from the "dynamical packet size adjusting". We hope it can improve the network transmission efficiency with heavy load on the network by packet size adjusting dynamically.

目錄
中文摘要I
英文摘要（ABSTRACT）II
目錄III
表目錄VI
圖目錄VII
縮寫字對照X
第一章 緒論1
1.1 簡介1
1.2 研究動機與背景2
1.3 研究方法與步驟5
1.4 章節概要6
第二章 CSMA/CD網路之探討7
2.1 CSMA/CD網路特性7
2.1.1 訊框格式10
2.1.2 位址欄位12
2.1.3 訊框碰撞的處理方法13
2.2 IEEE標準802.3及乙太網路18
2.2.1 MAC子層協定19
2.2.2 CSMA/CD的效率20
第三章 實驗方法與實驗結果23
3.1 理論依據23
3.1.1 名詞定義23
3.1.2 乙太網路的容量25
3.2 網路偵測工具28
3.2.1 協定分析儀29
3.2.2 協定分析軟體29
3.2.3 網路管理軟體30
3.2.4 手持式診斷工具30
3.3 系統架構30
3.4 實驗步驟32
3.5 實驗結果35
3.5.1 對照組35
3.5.2 實驗組37
第四章 結論42
4.1 實驗限制42
4.1.1 網路頻寬42
4.1.2 環境重現的困難42
4.1.3 即時性42
4.1.4 智慧型hub的影響43
4.2 實驗結果43
4.2.1 封包毀損的原因43
4.2.2 調整封包大小的依據43
4.3 未來發展方向44
4.3.1 模擬更真實的網路情況44
4.3.2 實作44
4.3.3 理論分析44
4.3.4 無線網路上的應用45
4.4 結語45
參考文獻46
附錄A 實驗記錄49

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