Gateway Controlled Content Caching and Retrieval for Cache-and-Forward Networks

The cache-and-forward (CNF) architecture has recently been proposed as a "clean-slate" solution for efficient content delivery in the future Internet. The CNF architecture is based on the concept of hop-by-hop transport and in-network storage of content. In this paper, we investigate a gateway centric method for efficient content caching and routing in the CNF network. In this method, a content copy can get cached within an autonomous system (AS) while it is routed towards the destination, and thus subsequent requests can be satisfied faster. The caching location within an AS is determined by the gateway node, through a hashing function. We discuss the two alternatives of this method: one with uniform caching level for every content, and the other with varying caching levels. Through simulation studies, we show that the gateway-controlled CNF caching method can greatly improve content retrieval latencies over traditional solutions, such as three levels of caches placed by Hierarchical Caching, and mirror servers deployed by Content Distribution Networks (CDNs). This gateway-controlled caching method also outperforms a baseline CNF caching method that was discussed in earlier papers. Additionally, we study and compare the detailed performances of the two alternatives of this method. Finally we develop a mathematical model which gives an optimal solution to how the gateway makes caching decisions within an AS.