Energy Efficiency in IP over WDM Networks

Abstract: In the last decade, energy efficiency in backbone networks has become an important problem due to the significant growth in the Internet traffic. A very promising solution to solve this problem in Internet Protocol (IP) over Wavelength Division Multiplexing (WDM) networks is the Virtual Topology Adaptation approach, which permits adapting network resources by following a dynamic daily traffic profile. In this approach, virtual topology in the WDM layer adapts to the changes in the IP traffic, however, IP layer routing is following the conventional shortest path routing strategy being unaware of the lower layer adaptation. This thesis study aims to analyze the possibilities of power savings in WDM and IP layers in coordination and proposes multi-layer approaches for energy-efficient IP over WDM networks. Energy-efficient algorithms on a realistic scenario are considered where commercially available routers and their power consumption parameters are taken into account. Among these IP router systems, power consumption of single and multi-shelf systems are analyzed. Multi shelf system can accommodate multiple chassis in a rack while in the single shelf system only one chassis is employed. For networks with single-shelf routers, we propose an energy-aware IP traffic routing strategy in coordination with a virtual topology adaptation approach to save energy by following a dynamic daily traffic profile. Energy-efficient IP routing strategy offloads the traffic from the network resources running in extreme load levels resulting in stabilization in the virtual topology and improvement in energy-efficiency. It is shown that using this approach a considerable amount of energy is saved compared to the case of virtual topology adaptation without the IP layer involvement. Power consumption in networks composed of multi-shelf routers is studied and three different strategies for energy efficiency are proposed: one in the WDM layer, an Energy and Chassis-Aware Virtual Topology Adaptation (ECA-VTA), another in the IP layer, the Energy and Chassis-Aware IP Routing (ECA-IP), and a multi-layer strategy that combines ECA-VTA and ECA-IP (ECA-IP-VTA). Joint optimization of IP&WDM layers significantly reduces power consumption and number of changes in the virtual-topology compared with single-layer approach.