Due to the proliferation of mobile devices such as smart phones and tablet computers, and increase in the speed of network devices to forward data, the Internet traffic has increased manyfold compare to a decade ago. Energy consumed by network devices handling the network traffic has increased manyfold also. Researchers are not only focusing on battery oriented network such as wireless sensor and ad hoc networks on saving battery power to extend network life but are also focusing on wired network to save energy consumed by network devices. Energy consumed by wired network can be reduced by putting underutilized network devices or links to sleep. If a network device has a few links such as a backbone network device, it is better to consider underutilized device to put to sleep, but if a network device has many links such as in data centers network devices and campus networks devices, it is better to consider underutilized links to put to sleep. In this paper, we consider putting underutilized links to sleep. Off course, if all links of a network device are put to sleep, the device itself will be put to sleep. Furthermore, in this paper we consider OpenFlow-based network as it is software defined network and flexible to control network devices. Besides, OpenFlow is being standardized by big enterprises such as NEC, Google, Cisco, Microsoft etc. We evaluated our approach by simulation and compare it with node based approach to see its effectiveness. © 2014 SERSC.