In the virtual network, the VSwitch become an important element in the network. It is in charge of both forward management and virtual network function. We figure out that to evaluate the performance of VSwitch is not like the test on hardware (like using RFC2544). This draft introduces the gap of testing for virtual network performance. On chapter 2 we introduce the test practices which is the virtual test bad setup and benchmark test. On chapter three, we analysis the gap of virtual network performance test.