On randomized request redirection in hierarchical caching systems

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. 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.