標籤交換網路下具有服務品質路由安排之研究

Study of QoS Path Arrangement in MPLS Networks

黃建欽 陳彥文

國立中央大學通訊工程研究所

ywchen@ee.ncu.edu.tw

Jian-Chin Huang, Yen-Wen Chen

Dept. of Communication Engineering

National Central University

ywchen@ee.ncu.edu.tw

摘要

網際網路標準制定組織(Internet Engineering Task Force，IETF)所提出的多重協定標籤交換技術(Multi-protocol Label Switching，MPLS)整合各種IP交換技術的優點，引入標籤(Label)的觀念，來提升整體網路的運作效率，加上其明確路由安排機制可使整體網路資源利用達理想化，並可提供較佳的服務品質(QoS)支援。本論文的主要研究重點在探討MPLS網路的標籤交換路徑的安排(LSP Assignment)，並考量不同服務等級路徑特性，將資源作有效的分配，以期達到不同連線服務之需求。LSP路由演算法於本論文中列舉Best-fit Shortest Path Algorithm (BSP)以及Worst-shortest Path Algorithm (WSP)兩種演算法，並針對不同等級的服務分別來做路徑選擇模擬之比較。經由考慮優先權安排LSP，希望可以達到服務品質之保障。而為讓網路中的鏈結(Link)頻寬的分配更具效率，在論文中亦提出伸縮限制頻寬(Elastic Constrained Bandwidth)的配置方式，由模擬結果得知，此配置方式可有效紓解高優先權路徑過於集中之缺點。

關鍵詞：標籤交換、選徑、服務品質保證

Abstract

Internet Engineering Task Force (IETF) has proposed the Multi-Protocol Label Switch (MPLS) to integrate various IP technologies. By using the label concept, MPLS provides the explicit routing mechanism to increase the overall performance and to support a better quality of services (QoS). This paper focuses on the assignment of label switch path (LSP) over MPLS networks. Network resources are effectively allocated for label switch paths according to their different service level requirements. In this paper, the best-fit Shortest Path Algorithm (BSP) and the worst-shortest Path Algorithm (WSP) are proposed for the selection of path routes. And the priority is also considered during the path selection. We also proposed the elastic constrained bandwidth scheme to disperse the high priority and low priority paths. The simulation results show that the proposed scheme demonstrates a quite good performance for the assignment of label switch paths.

Keywords: Label Switch, Routing, Quality of Services