Due to a mismatch between downloading and caching content, the network may not gain significant benefit from the sophisticated in-network caching of information-centric networking (ICN) architectures by using a basic caching mechanism. This paper aims to seek an effective caching decision policy to improve the content dissemination in ICN. We propose PopCache-a caching decision policy with respect to the content popularity-that allows an individual ICN router to cache content more or less in accordance with the popularity characteristic of the content. We propose an analytical model to evaluate the performance of different caching decision policies in terms of the server-hit rate and expected round-trip time. The analysis confirmed by simulation results shows that PopCache yields the lowest expected round-trip time compared with three benchmark caching decision policies, i.e., the always, fixed probability and path-capacity-based probability, and PopCache provides the server-hit rate comparable to the lowest ones.

No abstract

Purpose We investigated the communication bandwidth (CB) limitation for remote robotics surgery (RRS) using hinotori™ (Medicaroid, Kobe, Japan). Methods The operating rooms of the Hokkaido University Hospital and Kyushu University Hospital were connected using the Science Information NETwork (SINET). The minimum required CB for the RRS was verified by decreasing the CB from 500 to 100 Mbps. Ten surgeons were tested on a task (intracorporeal suturing) at different levels of video compression (VC) (VC1: 120 Mbps, VC2: 40 Mbps, VC3: 20 Mbps) with the minimum required CB, and assessed based on the task completion time, Global Evaluative Assessment of Robotic Skills (GEARS), and System and Piper Fatigue Scale-12 (PFS-12). Results Packet loss was observed at 3–7% and image degradation was observed at 145 Mbps CB. The task performance with VC1 was significantly worse than that with VC2 and VC3 according to the task completion time (VC1 vs VC2, P = 0.032; VC1 vs. VC3, P = 0.032), GEARS (VC1 vs VC2; P = 0.029, VC1 vs VC3; P = 0.031), and PFS-12 (VC1 vs. VC2; P = 0.032, VC1 vs. VC3; P = 0.032) with 145 Mbps. Conclusion Our findings provide evidence that RRS using hinotori™ requires a CB ≥ 150 Mbps. We also found that when there is insufficient CB, RRS can be continued by compressing the image.

No abstract

The Japanese academic backbone network has been providing a variety of multilayer network services to support a wide range of research and education activities for more than 700 universities and research institutions. The new version, called SINET4, was launched in 2011 in order to enhance the service availability and the network bandwidth as well as to expand the service menu. Its enhanced service availability was unexpectedly verified by the disastrous March 11 Great East Japan Earthquake, when the network managed not to stop service operation even after the earthquake. This paper describes the design and implementation of SINET4 in terms of multiple service provision, netPreliminary results for the contents of this paper have been presented at the international workshop on reliable network design and modeling (RNDM) 2011.