On the Delay Scaling Laws of Cache Networks

The Internet is becoming more and more content-oriented. CDN (Content Distribution Networks) has been a popular architecture compatible with the current Internet, and a new revolutionary paradigm such as ICN (Information Centric Networking) has studied. One of the main components in both CDN and ICN is considering cache on network. Despite a surge of extensive use of cache in the current and future Internet architectures, analysis on the performance of general cache networks are still quite limited due to complex inter-plays among various components and thus analytical intractability. Due to mathematical tractability, we consider 'static' cache policies and study asymptotic delay performance of those policies in cache networks, in particular, focusing on the impact of heterogeneous content popularities and nodes' geographical 'importances' in caching policies. Furthermore, our simulation results suggest that they perform quite similarly as popular 'dynamic' policies such as LFU (Least-Frequently-Used) and LRU (Least-Recently-Used). We believe that our theoretical findings provide useful engineering implications such as when and how various factors have impact on caching performance.