1. A method, comprising: communicating as a device within a directed acyclic graph (DAG) in a computer network; storing Internet Protocol (IP) routes at the device corresponding to upward traffic from the device directed toward a root of the DAG; IP-routing upward traffic based on the IP routes; storing labels at the device corresponding to downward traffic from the device directed away from the root of the DAG; and label-switching downward traffic based on the labels.