Coordinated caching in planet-scale CDNs: Analysis of feasibility and benefits

Video Content Distribution Networks (CDNs) serve a significant fraction of the Internet traffic through a global network of cache servers. In a planet-scale CDN with millions of videos, cache servers only consider their own request patterns for managing their content. We analyze how, in the absence of cooperative caching, the knowledge of requests in remote serving locations can lead to better caching decisions overall and can reduce serving costs. We call this practice cache coordination. Our analyses in this paper are based on actual video workload data from a global CDN. We analyze the spatial correlation of video popularities worldwide, the effectiveness and feasibility of cache coordination, and its scalability: from a city to across countries.