Datacenter networks (particularly, in clouds) nowadays support varieties of services from customers, and a novel paradigm, Software Defined Networking (SDN), is proposed to offer flexible application-aware management of these networks. However, as networks keep scaling up, many difficulties arise. Unlike prior studies on the data plane in SDN, this paper investigates the increasing complexity from deploying the control plane and proposes a novel economical and reconfigurable hybrid-band control mechanism (named ERIC) for large-scale SDN networks. Comparing to the state-of-the-art control mechanism (out-of-band), ERIC is much simpler and provides more reliability. Moreover, the number of switches used in the ERIC control plane is only 25% of that in the out-of-band control plane with 9% throughput differences. As a result, ERIC is proven suitable for datacenters due to low cost and high flexibility and can be applied to large-scale network deployments.