There is described a method for operating a proxy in a network function virtualization (NFV) system. The NFV system comprises a virtualized network function (VNF) manager for managing a VNF, a virtualized infrastructure manager (VIM) for managing a resource, and a NFV orchestrator. The method comprises: receiving a resource allocation request for the VIM from the VNF manager; sending the resource allocation request to a component of the VIM; receiving a response to the resource allocation request from the component of the VIM; and sending the response to the NFV orchestrator.