Energy saving is a really interesting topic in today's networks. Indeed Information and Communication Technologies (ICT) systems are energy greedy, they require more and more energy and as energy is more and more expensive we seek to save it. Accordingly, energy saving has recently received considerable attention, as a promising approach for delivering ICT services with environmentally conscious use of technology by implementing energy aware strategies in networks infrastructures which lead to improve network resources utilization. Thus this paper addresses the issue of energy consumption in telecommunication networks and especially in Carrier-Ethernet networks. We review and describe relevant works currently proposed for energy-efficient operation of wired network infrastructure. Besides surveying some of the different technical issues that researchers are currently facing to reduce the energy consumption in networking, this paper identifies some of the remaining key research challenges that arise when such energy-saving techniques are extended for use in Carrier Ethernet networks.