臺灣博碩士論文加值系統

在目前蓬勃發展的網際網路中，Peer-to-Peer (P2P)分享網路越來越普及，但是大多數P2P通訊協定在設計時，都是以傳統的有線網路作為基本環境。若網路環境改為目前常見的無線網路時，現有的P2P通訊協定在傳輸上將會遭遇到許多的問題與挑戰。例如節點在無線網路中，如果受到網路本身不穩定的狀況，容易使P2P網路上的節點離開或是過於頻繁地進出P2P網路，造成路由資訊維護與資源查詢的困難。在檢索資源時容易被這些過時或已失效的資訊導引到錯誤的節點，造成檢索的失敗，導致找到資源的時間與困難度大增。
本文以使用Distributed Hash Table (DHT)的Chord通訊協定作為機制實做的環境，將所設計的機制整合到 Chord 協定，設計出 MobileRobust-Chord(MR-Chord)。主要目的在於無線網路環境下，維護節點中 Finger Table 的正確性，來讓這些分散在各個節點Finger Table 中的路由資訊能夠有更高的正確率，進而提升我們在無線網路使用 P2P 技術時的資源檢索成功率、檢索的平均時間與減少 Lookup Table 的時間。

In the recent years, Peer-to-Peer (P2P) sharing network has become very popular in the Internet. However, most P2P protocols are designed for traditional wired networks. When deployed in wireless network environment, many challenges are encountered. For instance, the nodes in an unstable wireless network tend to leave or rejoin the P2P network easily. In this case, the routing information in every node must become overdue, which may lead to lookup failures when the nodes retrieve these overdue routing information.
In this thesis, we propose a modified Chord protocol called MobileRobust-Chord (MR-Chord). MR-Chord is designed with the aim of keeping the Finger Table fresh. To achieve this goal, we have modified the Distributed Hash Table (DHT)-based protocol – a Chord Protocol – in such a way that the Finger Table is kept updated to provide the necessary lookup services in the P2P network. Simulations studies show that our proposed MR-Chord protocol outperforms the original Chord protocol in the following aspects: (1) increase in the lookup success rate and overlay consistency, (2) reduction of the lookup delay time.

致謝...I
ABSTRACT...II
摘要...III
CONTENTS...IV
FIGURES...VI
TABLES...VIII
CHAPTER 1 INTRODUCTION...1
1.1. Peer-to-Peer Networks...1
1.2. Mobile Peer-to Peer Network and Challenges...2
1.3. Thesis Outline...4
CHAPTER 2 BACKGROUND WORK...6
2.1 Distributed Hash Table (DHT)...6
2.2 Chord Protocol...7
2.3 Chord and Other Protocols in Wireless Network Environment...11
2.4 Other Enhancements to the Chord Algorithm...12
CHAPTER 3 PROPOSED DESIGN...14
3.1 The Problem of Chord Operating in Wireless Network Environment...14
3.2 MobileRobust-Chord...16
3.2.1 Modification in Finger Table...16
3.2.2 Real-Time Fix Scheme...18
3.2.3 By-Detect Fix Scheme...22
3.2.4 Summary of MR-Chord...24
CHAPTER 4 PERFORMANCE EVALUATION...25
4.1 Simulation Setup...26
4.2 Performance Metrics...26
4.3 Simulation Results...27
4.3.1 Lookup Success Rate...27
4.3.2 Lookup Delay Time...32
4.3.3 Overlay Consistency...35
4.3.4 Lookup Hop Count...39
4.3.5 Total Network Load...43
CHAPTER 5 CONCLUSION AND FUTURE WORK...47
REFERENCE...48

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