隨著Internet的發展，愈來愈多的人相信，未來的電信網路將是基於IP技術的網路，而SIP（Session Initiation Protocol）挾帶方法簡單、擴充性佳和開放協議的優勢，儼然成為VoIP（Voice-over-IP）研究主流。現今SIP使用的主從式架構（Client-Server），雖然架構簡單、維護容易，但是卻有服務品質的優劣需仰賴伺服器性能之缺陷，為改善此缺陷，IETF（The Internet Engineering Task Force）草案討論了將P2P（Peer-to-Peer）架構應用於SIP的議題，希望藉由P2P架構，良好的容錯性和傳輸效能，提供良好SIP服務品質。
在本篇論文中以Chord為架構基礎，實做P2PSIP架構於嵌入式用戶端裝置（User Agent）為目的。針對SIP網路電話之特性，修改Chord部分演算法，以符合SIP網路電話之需求，且更針對此演算法進行調整，使之更適用於使用者不斷加入與離開之情況，讓Chord演算法真正的實現於SIP協定之中，來完成P2P SIP的目標。

With the development of Internet, more and more people believe that the future telecommunication network will be constructed based on IP technology. Session Initiation Protocol (SIP), which has advantages of simple entrainment method, good scalability and open protocols, is the main research topic on Voice-over-IP (VoIP). Although the client-server architecture currently used by SIP is simple and easy to maintain, it has limitation wherein service quality needs to rely on server performance. To improve this, the Internet Engineering Task Force (IETF) has created a draft to discuss the application of P2P (Peer-to-Peer) architecture in SIP, and we hope that the draft can help to provide good SIP service quality on P2P architecture, such as good fault tolerance and transmission performance.
Our research is based on Chord architecture and aims to make P2P SIP architecture in an embedded User Agent. For the SIP internet telephone feature, we adjusts Chord algorithm to meet SIP internet telephone requirements. Furthermore, the adjustment to Chord makes it more applicable to the environment that users continuously join or leave, so that the revised Chord can be implemented with SIP protocol to achieve the P2P SIP goal.

致謝 I
摘要 II
Abstract III
Contents IV
List of Figures V
List of Tables VI
1. Introduction - 1 -
1.1. Motivation Research - 1 -
2. Related Work - 3 -
2.1. Concept of SIP - 3 -
2.2. Concept of P2P SIP - 4 -
2.3. Chord Protocol - 5 -
2.3.1. Scalable Key Location - 6 -
2.3.1.1. Finger Tables - 6 -
2.3.1.2. Find_successor - 7 -
2.3.2. Node Joins and Stabilizations - 8 -
2.3.2.1. Node Joins - 9 -
2.3.2.2. Node Stabilize - 9 -
3. System Architecture - 12 -
3.1. Hardware Architecture - 12 -
3.2. Software Architecture - 14 -
3.3. SIP UA Operation Flow - 15 -
4. Implementation - 18 -
4.1. P2P SIP Algorithm - 18 -
4.1.1. P2P_discovery - 19 -
4.1.2. P2P_routing - 20 -
4.2. Chord Algorithm - 21 -
4.2.1. Key maintaining - 21 -
4.2.2. Join and Leave - 21 -
4.2.3. Lookup - 23 -
4.3. Large Scale - 23 -
4.4. Simulation - 28 -
4.4.1. Simulation of Chord Structure - 29 -
4.4.2. Simulation Result - 31 -
Conclusions - 37 -
Bibliography - 39 -

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