A non-transitory computer-readable medium storing computer instructions for allocating an IP address for an instance in a network function virtualization (NFV) system, that when executed by one or more processors, cause the one or more processors to perform the steps of obtaining a first requirement of IP address allocation from VNFD by a first node in the NFV system, determining a second requirement of IP address allocation for the instance according to the first requirement; and sending to a second node in the NFV system the second requirement, wherein the IP address is allocated for the instance based upon the second requirement.