The most straightforward way to reduce network power consumption is to turn off idle links and nodes (switches/routers), which we call the power down approach. In a wired network, especially in a backbone network, many links are actually 'bundles' of multiple physical cables and line cards that can be shut down independently. In this paper, we study the following routing problem for green networking in wired networks: Given a set of end-to-end communication sessions, determine how to route data traffic through the network such that total power consumption is minimized by turning off unused cables in bundled links and nodes, subject to the constraint that the traffic demand of each session is satisfied. We present an integer linear programming to provide optimal solutions. We also present two fast and effective heuristic algorithms to solve the problem in polynomial time. It has been shown by simulation results based on the Abilene network and the NSF network that the proposed heuristic algorithms consistently provide close-to-optimal solutions.