Tsinghua Univ. China Telecom China Telecom Huawei Technologies This document describes a declarative policy model to describe the user's declarative on network policy. The declarative policy model is a specific data model specifies the desired state of the network system. It helps the service management to model the policy (a set of states described by constraints) that defines the final results of a VPN service without specifying how it is monitored and managed during its lifecycle. One application for Distributed Data Center (DDC) scenarios with policy enforcement is provided with details of how to convert high level declarative policy into lower level configurations.