Power-aware design of protected IP-over-WDM Networks with sleep-mode devices

Recently, great efforts have been made to reduce power consumption in optical networks. The adoption of the Wavelength Division Multiplexing (WDM) technique is expected to enable greener data transport, especially considering the envisioned increase of traffic requirements. One main approach used to achieve power savings consists in aggregating, especially during low-load periods, traffic flows in a few network links, so that power can be saved by switching-off some devices within the network. However, the need to ensure network resiliency against link and/or node failures imposes that some resources, reserved to protect connections, become available immediately after a failure occurs. Thus, it is crucial for the network to be able to set some devices into low-power sleep-mode, such that they can be rapidly re-activated. In this paper we focus on the power-efficiency of protected IP-over-WDM networks and compare two different protection strategies, namely Dedicated-Link and Dedicated-Path Protection (DLP and DPP, respectively), when low-power sleep-mode for devices used for protection is enabled. A mathematical modelization for a power-aware design with sleep-mode for DLP and DPP is proposed that allows us to show that substantial power savings, up to about 20%, can be achieved through sleep-mode. Power savings, up to 10-15%, are also obtained with respect to the case of a power-unaware design with sleep-mode. Finally, we show that, by employing sleep-mode for backup resources, it is possible to protect all the connection requests for a small additional power expenditure compared to the unprotected network scenario.