A Simulator to Assess Energy-Saving Techniques in Content Distribution Networks

The scalable and bandwidth-efficient delivery of IPTV services to an increasingly diverse set of screens requires the deployment of telco content distribution networks (CDNs). These CDNs are composed of cache servers located in the telco’s data centers close to the end user. The additional cache servers need to be designed for energy efficiency to limit the increase of data-center energy consumption. We analyze real HTTP adaptive-streaming traces from an operational telco CDN delivering IPTV to mobile devices to identify workload characteristics that can be exploited to conserve energy. We also present a trace-driven simulator that models the energy consumption of such a CDN down to the level of the cache-server disk to evaluate potential energy-saving techniques. The traces reveal cyclic load fluctuations that can be exploited to save energy in CDNs by varying the number of powered cache servers and disks according to the load.