Multilayer traffic engineering for energy efficiency

Automatically switched multilayer IP-over-optical networks offer extensive flexibility in adapting the network to offered IP/MPLS traffic. Multilayer traffic engineering (MLTE) takes advantage of this through online IP logical topology reconfiguration in addition to the more traditional rerouting. The main goal of MLTE is to optimize toward resource usage, bandwidth throughput and QoS performance. However, energy efficiency of ICT infrastructure and the network in particular more recently have become an important aspect as well. In this article, we will look how MLTE helps in improving network energy efficiency. For this we will explain how optimization toward power requirement relates to the traditional resource usage minimization objective, and how power requirement in the network can be modeled for the MLTE algorithm. We will discuss two cases where the merit of MLTE for energy efficiency is discussed. Firstly, we will examine the interaction of MLTE with hardware-based energy efficiency optimization techniques; for this we look at scaling back power requirements through the use of better chip technology, but also decreasing idle-power requirement only, using improved chip architecture. Secondly, as MLTE allows for fast responses to changing traffic, we will see how link switch-off during off-peak hours offers a straightforward option to reduce energy needs.