Recovering Content Availability at Failures in ICN

To be widely spread as a social infrastructure, ICN (information-centric networking) is required to sustain not only network availability, i.e., connectivity between operating routers, but also content availability, i.e., reachability to content, at network failures. In ICN, FIBs (forwarding information bases) at routers are configured so that content requests reach hosts of content providers having the originals of content. Hence, requests for content whose connectivity to originals is lost cannot be transferred in networks, and the content availability of these content items is lost. However, copies of unavailable content are possibly cached at one or more operating routers in ICN. Therefore, in this paper, we propose to recover content availability by promoting one copy cached at operating routers to the original and updating FIBs so that content requests are transferred to the newly-promoted original. We also propose a method of selecting one copy so that the minimum average distance to other operating routers is minimized when copies are cached at multiple operating routers. Through numerical evaluation, we show that the availability of about 5% to 20% unavailable content items are recovered by the proposed method.