利用標籤交換技術支援行動隨意網路的服務品質

Abstract

本論文主要之目的是要在行動隨意網(Mobile Ad-hoc Network)上加入Multi-Protocol Label Switching (MPLS)的機制，以加速無線網路的封包傳遞(Packet forwarding)速度以及支援End-to-End的服務品質(Quality of Services，QoS)。 無線區域網路可以分為Infrastructure和Ad-hoc兩種網路架構。無線Infrastructure網路是在有線骨幹網路末端設置無線網路的基地台(Access Point，AP)，行動主機(Mobile Node，MN)利用這些AP可以連結有線骨幹網路，進行資訊通訊，無線通訊僅發生於AP與MN之間。而Ad-hoc網路則不需要有線的骨幹網路，沒有AP的支援，MN利用無線網路介面彼此通訊。 根據Wireless World Research Forum (WWRF)和Information Society Technologies Advisory Group (ISTAG)兩個機構分別提出的兩份報告預測，未來的網路將廣泛使用Ad-hoc網路，因為Ad-hoc網路具有低成本、容易建構的優點，我們可以利用Ad-hoc網路填補Infrastructure骨幹網路不能涵蓋之處，作為Infrastructure骨幹網路的延伸(Extension)。此外，有鑑於多媒體傳輸的需求快速增加，各項QoS的要求亦不斷提昇，同時網路使用的安全存取機制也日益受到重視，未來QoS以及安全存取的需求也將會出現在Ad-hoc網路中，以便在含Mobile Ad-hoc Network的wireless Infrastructure上提供End-to-End的QoS以及安全存取的機制。 MPLS是由Internet Engineering Task Force (IETF)所提出來的的新一代封包傳遞技術。MPLS整合標籤交換(Label Swapping)和網路層路由(IP Routing)，利用標籤交換以及連線導向的方式取代傳統的hop-by-hop的IP routing，不但可以提升封包路由(Packet routing)的效能，同時也可以方便有效地支援各種QoS的頻寬保留與管理機制。 本論文主要之目的，就是要在Ad-hoc網路中藉由整合MPLS提供end-to-end的QoS。由於在有線骨幹網路部分，目前已經有較成熟的MPLS、QoS相關的研究，然而相對於Ad-hoc網路，其相關研究卻是鳳毛麟角，尚屬起步的階段。所以在本論文中，我們將特別針對Ad-hoc網路整合MPLS和其相關QoS 支援方法提出我們的研究方法。希望藉由改良MPLS Label distribution and switch的機制，在Ad-hoc網路中加入MPLS，並利用MPLS特點，進一步提出支援QoS的機制。並期望此開發機制，也能適用在wireline網路中，同時讓wireless及wireline網路在不需花更多的成本與資源之下，卻能有一致性的、端點到端點(end-to-end)的品質服務保證。而最終能開發出一種可以應用在無論是MANET、wireless infrastructured、甚至是wireline 的跨階層網路環境裡，支援QoS的MPLS機制。

This thesis aims to propose a scheme that can embed Multi-Protocol Label Switching (MPLS) mechanism into the Mobile Ad-hoc Network (MANET) to expedite packet forwarding, and support better Quality of Services in an Infrastructure network that is extended with MANETs. According to the configurations Wireless Local Area Networks (WLANs), WLANs can be categorized as the Infrastructure network and the MANET. In an Infrastructure network, base stations or Access points (APs) are placed at the edge of the wire-line backbone network and Mobile Nodes (MNs) could attach to the wire-line backbone network via APs. On the contrary, a MANET does not employ the wire-line backbone, and MNs communicate with one another via wireless LAN interface without the supports of APs. According to the reports from Wireless World Research Forum (WWRF) and Information Society Technologies Advisory Group (ISTAG), MANETs would be used extensively in the future because they are easy to deploy and the cost of their deployment is extremely low. It is expected that MANETs could be used to extend the coverage area of the Infrastructure network. On the other hand, because the multi-media data transmission grows rapidly, the support of Quality of Services (QoS) is becoming more and more important. However, supporting QoS in the MANET is still problematic and is a challenge research topic. Therefore, it is still difficult to provide end-to-end QoS services in the Infrastructure with MANET extensions. MPLS protocol is a new packet routing technology that integrates the layer-two label swapping forwarding paradigm with the network-layer IP routing. It adopts connection-oriented Label Swapping packet routing, instead of hop-by-hop IP routing, which makes MPLS more efficient in packet routing. Besides, the connection-oriented packet routing also makes MPLS very effective in QoS guaranteed services. The goal of our research is to embed MPLS into Mobile Ad-hoc networks so that we could provide end-to-end QoS services in the Infrastructure with MANET extentions. The developments of MPLS and QoS are very mature in the wire-line network. However, there is hardly any such research for the MANET counterpart. Therefore in this research, we will focus on the MPLS intergration and QoS supports for the MANET. We will first adapt the Label distribution and switching mechanism of MPLS to fit the characteristics of the MANET. The adapted MPLS will be carefully designed to interwork with the current MPLS infrastructure. Based on the adapted MPLS, we will then present how to support QoS in the MANET and provide end-to-end QoS services in the Infrastructure with MANET extentions. Simulation results show that we can indeed improve bandwidth efficiency, routing speed, and fault tolerance in MANET.