近年由於雲端運算的發展，各個雲端服務供應商相繼推出自家服務，在租用大量機器時勢必頇透過路由器作聯繫，並提供用戶操作設定，以及配置自家的網路拓撲。伴隨著虛擬化技術的發展，路由器也逐漸走向虛擬化時代，但虛擬路由器的效能一直是虛擬化技術探討的項目。 我們於Xen平台上分析從實體網卡收到封包後，得知Xen利用虛擬橋接器(Virtual Bridge)將封包送往DomU所運行的虛擬路由器(Virtual router)做轉送(Forwarding)的動作。實驗與其他研究皆發現若Dom0作為一個路由器時，其效能較高於DomU上的虛擬路由器，因為無頇將封包在Dom0與DomU之間傳遞等內部所做的額外耗時動作，因此本研究試著將虛擬路由器作轉送的動作交由Dom0的虛擬橋接器學習虛擬路由器之轉向路由，將後續封包流直接轉送。 本論文提出修改虛擬橋接器使其能有如Label Switch般能快速判斷封包是否屬於相同的flow，使得封包能不經過虛擬路由器而直接於虛擬橋接器上做轉送，因此大幅提高虛擬路由器的效能，並且能提供虛擬路由器QoS等服務。 Due to the recent development of cloud computing, cloud services providers have launched their own services. When you hire a large number of machines in the cloud must be linked through a router, and provides user settings, and configure their own network topology. With virtualization technology growing, router has gradually toward virtualization, but the performance of virtual router has been a research projects. We analyzed that packets have been received from the physical network card on Xen platform; we find that Xen utilize virtual bridge to determine packet belong to which virtual router that running on DomU and to do forwarding action. Experiments and other studies are found when Dom0 as a router, its performance higher than DomU, because packets will not be passed between the Dom0 and DomU and made additional time-consuming operation within Xen. In this paper, we tried to do forwarding by Dom0’s virtual bridge learning routing information allow the following packets flow directly forwarding. This paper presents to modify virtual bridge source code that similar to the label switch could quickly determine whether the same packets flow or not. This making the packet could directly bypass virtual router and forwarding by virtual bridge, therefore substantial increase the virtual router forwarding performance, and can provide QoS for virtual router.