IETF所提出的Stream Control Transmission Protocol (SCTP)，具有高度的延展性以及相容性，在多媒體資料的傳送上，可以取代目前常用的TCP和UDP外，使得SCTP有可能成為下一代IP網絡上的傳輸協定。
我們提出的機制，是針對SCTP中Multi-homed的特性加以改良更新，使得在兩個SCTP端點間有多條路徑時，不僅只利用主要路徑來傳輸正常的資料封包，而是使其它的路徑，也能分配到適當大小的資料封包，發揮它的效能，並且使各路徑能符合原來SCTP的擁塞控制(Congestion Control)演算法。此機制以增加SCTP資料流的有效傳輸率，進而改進網路整體的利用率為目標。我們所提出的機制，並且考慮到時時變動的真實網路環境，利用一個新增的Chunk做為量測使用，以此加入封包中實際傳送，去比較各路徑傳輸速度，再利用返回的SCTP確認封包(Ack Packet)通知發送端，使得發送端的SCTP端點能夠運用比較的結果，調整備用路徑上資料傳送量的大小。
為了驗證我們的機制，我們利用NS-2模擬器模擬的方法，並且建立不同的拓樸實驗、量測與討論分析，並與原本的SCTP做比較，來說明使用我們的機制確實可以增加傳輸率，並且提高網路利用率；而且在網路負載變動的情況下，更新式SCTP能自動調整備用路徑上的流量。

To support the transmission of real-time multimedia stream, Stream Control Transmission Protocol (SCTP) developed by IETF is considered to be more efficient because of its high-degree expandability and compatibility. Today we can observe that instead of using SCTP may become the transmission protocol of next-generation IP network.
In this Thesis, we propose a mechanism to upgrade TCP and UDP, the multi-home feature of SCTP to ensure that multiple paths can exist between two SCTP ends. Not only can the primary path continue to function, but the secondary paths covey part of data packets once the network congestion occurs. Considering the dynamic change of our Internet, the proposed mechanism can enhance the effectiveness of SCTP data transmission, and increase overall network utilization. Cutting user data into chunks in SCTP, we can analyze the transmission performance of individual path by measuring the transmission delay from the sender to the receiving end.
By modifying the simulator of NS-2, we set up different topologies in the experiment to analyze the performance of our mechanism. We compare the modified SCTP with the original SCTP to highlight our proposed mechanism in increasing throughput and network utilization by adjusting the background traffic on the paths.

第一章 導論………………………………………………1
1.1 研究動機……………………………………………1
1.2 研究方向……………………………………………1
1.3 論文架構……………………………………………3

第二章 SCTP 的介紹及相關研究………………………4
2.1 串流控制傳輸協定( SCTP )………………………5
2.2 SCTP的特點…………………………………………6
2.3關於SCTP的相關研究………………………………9
2.3.1 SCTP 的Congestion Control…………………10
2.3.2 SCTP的效能表現………………………………10
2.3.3 SCTP與TCP功能及應用的比較…………………11

第三章 利用SCTP達到負載平衡………………………12
3.1 SCTP封包及Chunk格式……………………………12
3.1.1 修改Data Chunk………………………………13
3.1.2 新增一量測用的Chunk：TimeMeas Chunk……14
3.1.3 修改Selective Acknowledgement (SACK) Chunk…15
3.2 封包傳送…………………………………………16
3.2.1比較路徑傳輸時間………………………………17
3.2.2避免不正確的重傳………………………………22
3.2.3 多條路徑同時傳送封包…………………………24
3.3 負載平衡 ( Load Balancing )…………………27

第四章 模擬與量測……………………………………28
4.1 模擬實驗一：SCTP 與M-SCTP比較………………28
4.1.1模擬實驗架構與設定……………………………28
4.1.2 實驗量測與分析討論…………………………30
4.2 模擬實驗二：SCTP 與 TCP 負載變動的網路…36
4.2.1 模擬實驗架構與設定…………………………36
4.2.2 模擬實驗二的量測統計與分析討論…………38
4.3 模擬實驗三：SCTP 與 TCP多負載變動的網路…39
4.3.1 實驗架構與設定…………………………………39
4.3.2 模擬實驗三的量測統計與分析討論……………41

第五章 結論與未來工作………………………………43
5.1 結論………………………………………………43
5.2 未來工作…………………………………………44

參考文獻………………………………………………45
索引……………………………………………………48

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[2] L. Coene, “Stream Control Transmission Protocol Applicability Statement”, RFC 3257, Internet Engineering Task Force, April 2002.
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[24] The Network Simulator - ns-2. http://www.isi.edu/nsnam/ns/.
[25] NS-2 SCTP Module Home Page. http://pel.cis.udel.edu.