While the 3N architecture has the advantages above, there is one important risk its design needs to avoid: robustness. Although the 3N architecture increase the robustness of control and management plane by a distributed manner, compared with that by a logically centralized manner, there are mechanisms which need to be carefully designed to ensure that the forwarding network still can work well when some links for control or management failed. In the worst case that the control network and management network are fully down, the forwarding network should be able to reconfigure itself to run necessary routing protocols, working the same as traditional networks.