Discovering in-network Caching Policies in NDN Networks from a Measurement Perspective

Caching is integral to Named Data Networking (NDN). Routers in NDN networks are encouraged to cache content and serve later requests from their caches. As NDN has evolved, researchers have realized that different caching schemes work better for different types of content and patterns of content requests. From a measurement perspective, this means that being able to determine the caching schemes in use within an NDN network can be essential to understanding the network's performance. In this paper, we investigate the feasibility of detecting NDN caching schemes via active measurement (i.e., by sending requests into the network and measuring responses) from edge systems (e.g., by users). We show it is possible to determine what algorithms routers are using to decide what content to cache. Furthermore, for stochastic caching schemes with fixed caching probabilities, we show it is possible to infer the caching probability. Finally, while we do not seek to understand routers' cache replacement policies (which we leave to future work), we find that the methods for determining the caching algorithm are robust to cross traffic that may impact the content of a router's cache.