ETRI DONG-EUI Univ. ETRI China Mobile The usage of multiple interfaces in a host causes other problems due to the multiplicity of available interfaces. If interface is changed during communication, the communication is disrupted. Multiple interfaces in a host do not support the simultaneous usage of multiple interfaces. In this document, we discuss how to solve the problems of interface change and simultaneous usage of multiple interfaces and propose a virtual interface which hides the multiple interfaces from the IP stack of host. And we describe the applicability of virtual interface into the problem of multiple interfaces in multiple interfaces PS document. This document provides the implementation guidelines of virtual interface for a multiple interface host.