In one embodiment, a device, such as a network management server, determines a traffic matrix of a mesh network, where the traffic matrix indicates an amount of traffic per type of traffic transitioning between the mesh network and a global computer network via one or more current root devices. One or more optimized root devices may then be selected for corresponding directed acyclic graphs (DAGs) based on the amount of traffic and type of traffic. As such, a DAG formation request may be transmitted to the selected root devices, carrying a characteristic for a corresponding DAG to form by the respective selected root devices that indicates which one or more types of traffic correspond to the corresponding DAG.