When applying Software-Defined Networks(SDN) to WANs,the SDN flexibility enables the cross-domain control to achieve a better control scalability.However,the control consistence is required by all the cross-domain services,to ensure the data plane configured in consensus for different domains.Such consistence process is complicated by potential failure and errors of WANs.In this paper,we propose a consistence layer to actively and passively snapshot the cross-domain control states,to reduce the complexities of service realizations.We implement the layer and evaluate performance in the PlanetLab testbed for the WAN emulation.The testbed conditions are extremely enlarged comparing to the real network.The results show its scalability,reliability and responsiveness in dealing with the control dynamics.In the normalized results,the active and passive snapshots are executed with the mean times of 1.873 s and 105 ms in135 controllers,indicating its readiness to be used in the real network. When applying Software-Defined Networks (SDN) to WANs, the SDN flexibility enables the cross-domain control to achieve a better control scalability. However, the control consistence is required by all the cross-domain services, to ensure the data plane configured in consensus for different domains.Such consistence process is complicated by potential failure and errors of WANs.In this paper, we propose a consistence layer to actively and passively snapshot the cross-domain control states, to reduce the complexities of service realizations .We implement the layer and evaluate performance in the PlanetLab testbed for the WAN emulation. The testbed conditions are extremely enlarged comparing to the real network. The results show its scalability, reliability and responsiveness in dealing with the control dynamics. the normalized results, the active and passive snapshots are executed with the mean times of 1.873 s and 105 ms in135 controllers, indicating its readiness to be used in the real network.