As internet traffic grows, the underlying infrastructure consumes increasing amounts of energy. During off-peak hours, large parts of the networks remain underutilized, presenting significant potential for energy savings. Existing Green Traffic Engineering approaches attempt to leverage this potential by switching off those parts of the networks that are not required for the routing of specific traffic matrices. When traffic changes, the approaches need to adapt rapidly, which is hard to achieve given the complexity of the problem. We take a fundamentally different approach: instead of considering a specific traffic matrix, we rely on a traffic-oblivious routing scheme. We discuss the NP-hard problem of activating as few connections as possible while still guaranteeing that any down-scaled traffic matrix $\varrho\cdot T$ can be routed, where $\varrho \in (0,1)$ and $T$ is any traffic matrix routable in the original network. We present a $\max(\frac{1}{\varrho\cdotλ_{\text{min}}},2)$-approximation algorithm for this problem, with $λ_{\text{min}}$ denoting the minimum number of connections between any two connected routers. Additionally, we propose two post-processing heuristics to further improve solution quality. Our evaluation shows that we can quickly generate near-optimal solutions. By design, our method avoids the need for frequent reconfigurations and offers a promising direction to achieve practical energy savings in backbone networks.

翻译：随着互联网流量的增长，底层基础设施消耗的能源日益增加。在非高峰时段，网络的大部分容量处于未充分利用状态，这为节能提供了显著潜力。现有的绿色流量工程方法试图通过关闭网络中特定流量矩阵路由所不需要的部分来利用这一潜力。当流量发生变化时，这些方法需要快速适应，而考虑到问题的复杂性，这很难实现。我们采用了一种根本不同的方法：不依赖于特定的流量矩阵，而是基于一种流量无关的路由方案。我们讨论了一个NP难问题：在保证任何按比例缩放的流量矩阵$\varrho\cdot T$均可路由的前提下，激活尽可能少的连接，其中$\varrho \in (0,1)$，$T$为原始网络中可路由的任意流量矩阵。针对该问题，我们提出了一种$\max(\frac{1}{\varrho\cdotλ_{\text{min}}},2)$近似算法，其中$λ_{\text{min}}$表示任意两个相连路由器之间的最小连接数。此外，我们提出了两种后处理启发式方法以进一步提升解的质量。评估结果表明，我们能够快速生成接近最优的解。通过设计，我们的方法避免了频繁重新配置的需求，为实现骨干网实际节能提供了一条有前景的路径。