To operate a reliable SDN network, the control plane should be robust in order to guarantee the correctness of traffic forwarding. For in-band control, the traffic flows along with the data plane without a dedicated control network. Thus, the failure of data plane may isolate the switches from control plane and lead to erroneous forwarding behavior. In this paper, we design a control plane, FASIC, which can bootstrap the control network autonomously and adaptively span the control plane with the control-link switching mechanism. By implementing our design with Open vSwitch (OVS), OpenDayLight OVSDB Integration (ODL-OVSDB) and Floodlight software, we demonstrate that FASIC is an in-band control solution which is feasible under support of the available SDN and OpenFlow resources. Compared with standard OVS, the experimental result shows that FASIC reduces 87.83% of control plane downtime under hard link failure and incurs zero downtime under congestion. The preemptive control-link switching can prevent the control-link failure when it suffers from heavy traffic load.