  Rising energy consumption of IT infrastructure concerns have spurred the
development of more power efficient networking equipment and algorithms. When
\emph{old} equipment just drew an almost constant amount of power regardless of
the traffic load, there were some efforts to minimize the total energy usage by
modifying routing decisions to aggregate traffic in a minimal set of links,
creating the opportunity to power off some unused equipment during low traffic
periods. New equipment, with power profile functions depending on the offered
load, presents new challenges for optimal routing. The goal now is not just to
power some links down, but to aggregate and/or spread the traffic so that
devices operate in their sweet spot in regards to network usage. In this paper
we present an algorithm that, making use of the ant colonization algorithm,
computes, in a decentralized manner, the routing tables so as to minimize
global energy consumption. Moreover, the resulting algorithm is also able to
track changes in the offered load and react to them in real time.
