臺灣博碩士論文加值系統

隨著網路多媒體應用的興起，服務品質的保証成為網路技術研究的一個重要議題。建立具服務品質保証傳輸通道的程序中，相當重要的一項工作便是服務品質路由。服務品質路由的主要功能是在網路中找尋符合服務品質要求的路徑。本論文的研究重點在於使用有限度泛流方式的具服務品質保証的路由方法。相較於使用定期收集的網路資源使用狀態、計算出符合要求路徑的作法，有限度泛流作法避免了狀態訊息傳播的負載、狀態資訊的不及時性問題、以及路徑計算的複雜度，同時也較節省網路節點的記憶空間，以及達到較短的連線建立時間。
先前使用訊息泛流路由方式的研究主要著重於如何減低泛流訊息的負載。然而，關於網路資源的使用效率卻較少被考慮。使用訊息泛流路由方式若搭配不當的資源保留策略，會造成非必要的資源佔用，而直接影響到整體網路的效能表現，包括連線成功建立的機會的減低，負載分配不均衡的問題，以及對傳統致力式資料流的傳送效能的影響等。
本研究提出了一個運用訊息泛流的路由方法，採用兩段式資源保留機制避免非必要的資源佔用，同時提出三個改良機制來提升整體網路的效能表現，特別是連線成功機會的提升。這三個機制包括了改良的泛流範圍限定機制、動態最佳路徑的選擇、以及備用路徑的增設。透過模擬實驗，比較了具泛流範圍限制機制的單段式和兩段式作法，結果顯示本研究所提出的改良方法，在持相當的訊息負載和連線建立時間的前提下，確實有效地增加了連線成功建立的機會，達到較高的資源使用效率。

Quality-of-Service (QoS) routing is extensively received for emerging distributed multimedia applications, which have stringent QoS requirements in terms of bandwidth, delay, delay jitter, cost or loss rate, etc. Essentially, QoS routing explores qualified routes between senders and receivers for establishing connections with some QoS guarantees. Previous studies on QoS routing can be classified into two categories: link-state based and probing based. Link-state approaches suffer from complexity of route computation, overhead of link-state dissemination, and imprecision of state information, while probing based approaches may incur tremendous message overhead and inefficient resource utilization.
This thesis proposes a probing based, two-pass bandwidth-constrained routing algorithm based on bounded flooding. It achieves high performance and efficiency by employing three enhancements. First, the node-level distance test is used to reduce memory requirement and computational power on intermediate nodes. Second, dynamic route selection efficiently chooses better route for reservation and distributes traffic loads through the entire network. Third, a backup path is maintained on the destination node to deal with “reservation failure”, the basic problem of two-pass reservation schemes.
Through simulation evaluations, the proposed algorithm outperforms similar two-pass algorithms in terms of average call acceptance rate with comparable average call setup time and message overhead. Further issues are also addressed in the end of this article.

第一章 前言...........................................1
第二章 背景及相關研究.................................2
第三章 有限度泛流之兩段式具服務品質路由方法...........3
第四章 效能評估.......................................4
第五章 結語...........................................5
CHAPTER 1 INTRODUCTION................................1
CHAPTER 2 BACKGROUND AND RELATED WORKS................5
2.1 Two Reservation Schemes............................5
2.2 Related Works on Flooding Based QoS Routing........7
CHAPTER 3 THE PROPOSED ALGORITHM.....................13
3.1 Probing and Reservation Phases....................13
3.2 Messages and Tables...............................15
3.3 Node-Level Distance Test..........................17
3.4 Dynamic Route Selection...........................19
3.5 Backup Path Reservation...........................24
CHAPTER 4 PERFORMANCE EVALUATION.....................29
4.1 Performance Metrics...............................29
4.2 Simulation Models.................................30
4.3 Simulation Results................................31
CHAPTER 5 CONCLUSIONS................................34
REFERENCES............................................35

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