使用虛擬網路概念之高可靠度乙太接取網路架構

Abstract

乙太網路被視為佈建與接取服務網路的一項關鍵技術。它具有，高擴充性、高頻寬、低價位與便於部署的優點。不過，乙太網路的主要缺點是它缺乏電信設備服務等級的效能。論文中，我們提出了可以符合電信設備等級的高容錯乙太服務接取網路架構，藉由我們提出的建議案亦可大大降低乙太接取網路的佈建成本。 因此，我們提出了以虛擬網路概念為基礎的高容錯乙太服務接取網路架構。雖然虛擬網路並非新的概念，但就我們所知、我們是第一個提出並將之應用於支援電信設備服務等級的乙太服務接取網路。為了達到服務不中斷的電信服務等級目的，我們由ㄧ加一備援架構來建構我們提出的高容錯乙太服務接取網路架構。值得ㄧ提的是，我們所提出的建議案是非常簡易且僅用軟體就可完全實踐。 另外、我們藉要求使用支援最基本之虛擬區域網路功能的第二層交換器來建構高容錯乙太服務接取網路。這些第二層交換器在ㄧ般市售價格裡，大約七千新台幣。在我們提出的架構裡，我們能服務多達512用戶於乙太服務接取網路裡。。若應用於專屬網路、則可兼具延展性的需求。 為了評斷我們提出的架構是屬於電信設備服務等級的架構，我們使用了”連續時間之馬可夫鏈 ”來做分析與驗證。透過分析、我們可以發現在連續時間之馬可夫鏈判定下，我們所提出的虛擬網路概念之高容錯乙太服務接取網路架構是可以符合電信設備服務等級。

Ethernet is envisioned as a key technology to recent deployments of service network. Ethernet features in high scalability, very high bandwidth provisioning, inexpensive, and easy deployment. However, the major drawback of Ethernet is its lack of supporting carrier grade services. In this thesis, we consider to support carrier grade service for Ethernet access network. In addition, we aim at further reducing the switch cost by requiring less functionality in switches. To do so, we propose a virtual-network-based access architecture. The concept of virtual network is not new. Nevertheless, as far as we know, we are the first to extend its usage to study the fault-tolerant-related issues in Ethernet access networks. In this thesis, we elaborate on determining the configuration of virtual networks so that the service can be recovered when a fault occurs. Our goals for the virtual network configuration are basically requiring least VLAN functionalities in switches, enabling fast service recovery process upon an occurrence of faulty link/switch, and sustaining the scalability of access network. Our proposal basically employs the one-plus-one backup principle to enable fault tolerance. Our proposed protocol is very simple and can be carried out entirely by software approach. Besides, our proposed architecture only needs minimum VLAN function for switches. Traditional application in our proposal, we can service up to 512 customer networks in the access network. In military network and the proprietary network, the scalability would not be the issue. To evaluate the degree of carrier grade service of our proposal, fault-tolerant-related behavior is modeled by a continuous-time Markov chain (CTMC). Through the analysis, we also aim at discovering the rule of thumb to keep high degree of carrier grade.