A Survey of Caching Policies and Forwarding Mechanisms in Information-Centric Networking

Information-centric networking (ICN), an alternative to the host-centric model of the current Internet infrastructure, focuses on the distribution and retrieval of content instead of the transfer of information between specific endpoints. In order to achieve this, ICN is based on the paradigm of publish-subscribe and the concepts of naming and in-network caching. Current approaches to ICN employ caches within networks to minimize the latency of information retrieval. Content may be distributed either in caches along the delivery path(s), on-path caching or in any cache within a network, off-path caching. While approaches to off-path caching are comparable to traditional approaches for content replication and Web caching, approaches to on-path caching are specific to the ICN area. The purpose of this paper is to provide a review of the caching problem in ICN, with a focus on on-path caching. To this end, a detailed analysis of the existing caching policies and forwarding mechanisms that complement these policies is given. A number of criteria such as the caching model and level of operation and the evaluation parameters used in the evaluation of the existing caching policies are being employed to derive a taxonomy for on-path caching and highlight the trends and evaluation issues in this area. A discussion driven by the advantages and disadvantages of the existing caching policies and the challenges and open questions in on-path caching is finally being held.