Modeling and analysis of an expiration-based hierarchical caching system

Caching is an important means to scale up the growth of the Internet. Weak consistency is a major approach used in Web caching and has been deployed in various forms. This paper investigates some properties and performance issues of an expiration-based caching system. We focus on a hierarchical caching system based on the Time-To-Live (TTL) expiration mechanism and present a basic model for such a system. By analyzing the intrinsic TTL timing behavior in the basic model, we derive several important performance metrics from the perspective of the caching system and end users, respectively. Our results offer some basic understanding of a hierarchical caching system based on the weak consistency paradigm.