隨著網際網路快速的發展，傳統的網路架構沒有辦法提供傳輸品質保證的服務，尤其對於即時性的應用程式而言，如何能滿足其所要求的頻寬並能在傳輸期間內給予傳輸品質保證變成是現今網際網路領域上的一大課題。為了解決這個問題，IETF組織先後提出二個網路架構，分別是整合式服務(Int-Serv)架構及差別式服務(Diff-Serv)架構。整合式服務是針對每一個資料流提供點對點式的傳輸服務品質保證，並且利用資源保留協定(RSVP)作為訊號控制的協定，因而完成資源預留的程序。然而，整合式服務架構在實際的配置上會產生伸展性的問題(Scalability Problem)。差別式服務依據路由器所在位置而將其分成兩類，分別是：邊界路由器(Edge Router)與內部路由器(Core Router)，差別式服務更針對每個路由器定義了不同程度的傳送服務，藉由在每個路由器上的速率控制而達到差別式的傳輸服務品質保證。但差別式服務架構也面臨一些新的問題，如：粗略的服務品質保證及缺乏點對點式服務保證的考量。
本篇論文為了解決差別式架構下的缺失，因此提出了一個解決方法來使之能提供嚴格式的傳輸服務品質保證，最主要的關鍵是對於即時性交通採取單一資料流式(Per-flow)來取代資料叢集式(Aggregate)的傳輸服務品質保證，為了達成此目的，我們更運用了三個機制：區域集中式的資源管理、集中式路由配置與頻寬預留協定。我們更進一步的利用頻寬預留協定(BRP)與資源保留協定(RSVP)做參數轉換，使得此嚴格式的傳輸服務能夠與整合式服務下之保證式服務(Guaranteed Service)做結合，提供一個跨越不同網路架構並兼顧傳輸服務品質保證的整合性服務。

透過軟體模擬，我們發現此新網路架構能夠有效地降低即時性交通的碰撞機率與平均封包延遲，因此能為即時性應用程式提供嚴格式的傳輸服務品質保證。

In traditional IP-based network, all the Internet traffic is delivered in best-effort manner without any QoS guarantee. As Internet multimedia applications become popular, current network framework cannot provide enough quality of service to meet the demand for a variety of new applications. In order to solve the problem, Internet Engineering Task Force (IETF) has proposed two network frameworks successively: Integrated Services (Int-Serv) and Differentiated Services (Diff-Serv). Resource Reservation Protocol (RSVP) is employed in Int-Serv to make the reservation along routing path before traffic is delivered. Diff-Serv specifies different forwarding treatments to provide a number of services corresponding to different QoS provisions.
The Expedited Forwarding per-hop behavior (EF PHB) is specified to provide a low loss, low latency, assured bandwidth and end-to-end service through Diff-Serv domains. The EF PHB is implemented by configuring nodes such that the EF aggregate has a minimum departure rate independent of other traffic at the node. However, only the rate configuration of EF PHB is not able to be a hard QoS guaranteed service which must experience the strict constraint of QoS specification.

In this thesis, we aim to provide a hard QoS guaranteed service with end-to-end behavior across domains in Diff-Serv. We add bandwidth reservation process for each EF session in Diff-Serv with strict QoS provision. For this purpose, we utilize three mechanisms for the new framework: (1) local centralized resource management, (2) centralized route discovery, (3) a sender-initialized signaling protocol. The signaling protocol we proposed is named Bandwidth Reservation Protocol (BRP) and it is responsible for exchanging messages between bandwidth broker and the edge router. By simulation, we evaluate the performance of our proposal against current Diff-Serv framework. Our approach has excellent performance on congestion probability and average delay for both short-term and long-term EF traffic.

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