Periods of low load have been used for the scheduling of non-interactive tasks since the early stages of computing. Nowadays, the scheduling of bulk transfers—i.e., large-volume transfers without precise timing, such as database distribution, resources replication or backups—stands out among such tasks, given its direct effect on both the performance and billing of networks. Through visual inspection of traffic-demand curves of diverse points of presence (PoP), either a network, link, Internet service provider or Internet exchange point, it becomes apparent that low-use periods of bandwidth demands occur at early morning, showing a noticeable convex shape. Such observation led us to study and model the time when such demands reach their minimum, on what we have named valley time of a PoP, as an approximation to the ideal moment to carry out bulk transfers. After studying and modeling single-PoP scenarios both temporally and spatially seeking homogeneity in the phenomenon, as well as its extension to multi-PoP scenarios or paths—a meta-PoP constructed as the aggregation of several single PoPs—, we propose a final predictor system for the valley time. This tool works as an oracle for scheduling bulk transfers, with different versions according to time scales and the desired trade-off between precision and complexity. The evaluation of the system, named VTP, has proven its usefulness with errors below an hour on estimating the occurrence of valley times, as well as errors around 10% in terms of bandwidth between the prediction and actual valley traffic.

从计算的早期阶段开始，就已经将低负载时段用于非交互式任务的调度。如今，由于批量传输对网络的性能和计费都有直接影响，因此在这些任务中，调度批量传输（即没有精确定时的大容量传输，例如数据库分发，资源复制或备份）显得尤为突出。通过目视检查网络，链路，Internet服务提供商或Internet交换点等不同接入点（PoP）的流量需求曲线，很明显，带宽需求的低使用期发生在清晨，这表明凸形。这样的观察促使我们研究和建模了此类需求达到最低要求的时间，即我们所说的PoP的谷值时间，接近进行批量转移的理想时间。在研究和建模单一PoP场景后，在时间和空间上寻求现象的同质性，以及将其扩展到多PoP场景或路径（一种由多个单一PoP聚合而成的元PoP）之后，我们提出了最终的预测变量谷时间的系统。该工具可作为调度批量传输的预言机，根据时间范围以及精度和复杂性之间的所需折衷，可以使用不同的版本。该系统的评估名为 我们提出了山谷时间的最终预测系统。该工具可作为调度批量传输的预言机，根据时间范围以及精度和复杂性之间的所需折衷，可以使用不同的版本。该系统的评估名为 我们提出了山谷时间的最终预测系统。该工具可作为调度批量传输的预言机，根据时间范围以及精度和复杂性之间的所需折衷，可以使用不同的版本。该系统的评估名为VTP证明了其有用性，它在估计谷底时间的发生时会出现一个小时以下的误差，并且在预测与实际谷底流量之间的带宽方面的误差约为10％。