Valley times in the Spanish academic network

The scheduling of bulk transfers such as database distribution, resources replication and security backups, and other non-time-critical tasks has a direct effect on both the performance and cost of a network. We propose to face this problem by studying the valley times - i.e., the minimum use during off-peak periods of a network - as suitable moments to carry out such tasks. To do so, we characterize them considering the valley-hour, which we define as the opposite to the well-known variable busy-hour. Our analysis, based on 6-year-long measurements from 12 points of presence in the Spanish Research and Education Network (RedIRIS), has guided us to model the valley-hour as a Gaussian process. After that, we compare its behavior in different points and detect the main factors that explain its variance, finding significant heterogeneity. With the resulting conclusions, we have proposed a system to predict valley-hours in RedIRIS with errors below an hour for most of the cases.