A node device for forming a multi-hop network is provided. The node device is configured to discover two routing topologies: a normal routing topology for normal
data transmission and a preferred topology for prioritized
data transmission. The normal
route is discovered for all data nodes in an IoT network, and the preferred
route is discovered for only the preferred data nodes. The normal data
route (D-route) is discovered using a distance-based route discovery protocol (RPL), and the preferred route (P-route) is optimally discovered for only the preferred data nodes to minimize route overlap, route
transmission time, and route length. The node device includes a
transceiver configured to transmit and receive normal data in a destination-oriented
directed acyclic graph (DODAG)-based topology and transmit and receive priority data in the optimal routing topology; a memory configured to store a computer-
executable program including a communication mode (CM), a multirate link count (MLC), a route overlap degree (DRO), neighbor node information, route
transmission time, and route length; and a processor configured to execute the steps of the computer-
executable program. The steps include finding a D route and finding a P route, where finding a P route includes finding a non-circular route, finding a minimum overlap route, finding a minimum
transmission time route, and finding a minimum length route.