Green Traffic Engineering encompasses network design and traffic routing strategies that aim at reducing the power consumption of a backbone network. We argue that turning off linecards is the most effective approach to reach this goal. Thus, we investigate the problem of minimizing the number of active line cards in a network while simultaneously allowing a multi-commodity flow being routed and keeping the maximum link utilization below a certain threshold. In addition to proving this problem to be NP-hard, we present an optimal ILP-based algorithm as well as a heuristic based on 2-Segment Routing. Lastly, we evaluate both approaches on real-world networks obtained from the Repetita Framework and a globally operating Internet Service Provider. The results of this evaluation indicate that our heuristic is not only close to optimal but significantly faster than the optimal algorithm, making it viable in practice.

翻译：绿色流量工程涵盖旨在降低骨干网络能耗的网络设计与流量路由策略。我们认为关闭线卡是实现此目标最有效的途径。为此，我们研究了在同时允许多商品流路由且保持最大链路利用率低于特定阈值的前提下，最小化网络中激活线卡数量的问题。除证明该问题为NP难问题外，我们提出了一个基于整数线性规划的最优算法以及一个基于2-分段路由的启发式算法。最后，我们在从Repetita框架及全球运营的互联网服务提供商获取的真实网络数据上对两种方法进行了评估。评估结果表明，我们的启发式算法不仅接近最优解，且显著快于最优算法，从而使其在实际中具备可行性。