Abstract: Virtualization and scalability & programmability are two key characteristics to be supported by network devices for the development of Internet. In recent years, researchers have proposed many prototypes based on these two requirements. The virtual router is one representative prototype, which realizes these two requirements by the virtualization technique and scalable routing software. However, due to the overhead of virtualization techniques, the forwarding performance of a virtual router is usually limited. This paper investigates different virtualization techniques and scalable routing software, establishes the test-bed and evaluates the forwarding performance under different virtualization techniques, and conducts the assessment on several typical virtual I/O acceleration techniques.