A Two-tiered Caching Scheme for Information-Centric Networks

In information centric networking (ICN), by default, forwarder nodes along the paths from content producers to consumers, cache and reuse content chunks ubiquitously, invoking the Least Recently Used (LRU) replacement policy when needed. Due to the cache filtering effect, this ubiquitous-LRU strategy is inefficient: popular contents that are cached a few hops away from the edge are of little utility. Most alternative proposals adopt unified on-path schemes that rely on popularity statistics or other global state information to improve the performance. In the Internet, it is difficult to imagine different administrative-entities exposing such information to each other, and so we argue that such schemes are not realistic; and secondly, a unified caching scheme across the network ignores the administrative autonomy, which is one of the tenets of the Internet. In this paper we argue for a two-tiered caching scheme that maintains an on-path caching scheme (e.g., Ubiquitous-LRU), yet embraces AS-autonomy by adding within the AS an off-path cooperative-caching and redundancy elimination, to make better use of caches in the edge where they are most valuable. We describe the implementation of our scheme and highlight the design choices to make the system practical. Our evaluation results show that our scheme can reduce cache misses and upstream traffic by up to 15% compared to the state-of-the-art.