1. A method, comprising: receiving one or more advertisements of smoothed path costs to a root node of a computer network represented by a directed acyclic graph (DAG) at a node in the network, each advertisement containing a field for a virtual gain factor (VGF); determining a local smoothed path cost from the node to the root node and a local VGF for each link of the node; computing a resulting smoothed path cost to the root node along with an associated VGF at the node based on the locally determined cost and locally determined VGF; and advertising the resulting smoothed path cost along with the associated VGF at the node to other nodes in the network.