On Randomized Request Redirection in Hierarchical Caching Systems

Abstract — Adopting Time-to-Live (TTL) based hierarchical caching systems is considered to be a viable approach to support Web content delivery under the weak consistency paradigm. However, with a strictly hierarchical structure in these systems, a single user request may trigger multiple consecutive miss events at cache servers of different levels. This undesirable miss synchronization can cause a sudden degradation of user-perceived performance in terms of response time. In this paper, we offer a comprehensive examination of this undesirable behavior and propose a randomized request redirection approach to circumvent the structural restrictions in TTL-based hierarchical caching systems. Performance analysis and evaluation indicate that the proposed approach can effectively rebalance server overhead and network delay, which in turn reduces end user response time. Index Terms — Internet, content delivery, hierarchical caching, weak consistency, miss synchronization I