Impact of Tohoku earthquake on R&E network in Japan

The Internet is one of the important infrastructures in our daily life, and its highly distributed and autonomous natures have been said to be robust against failures. This paper reports an impact of an unexpectedly large earthquake (M9.0) hit to the northern part of Japan at 14:46:18 on 11th March (UTC+9), 2011(the East Japan Earthquake) [2] on a nation-wide research and education network (SINET4 [10, 12, 13]) in Japan. We show that the network managed to run even after the earthquake thanks to two different levels of redundancies, though some physical links were damaged; consequently, the impact on the routing (both BGP and OSPF) was insignificant. At the epicenter area, some network nodes (i.e., universities) were disconnected from the network by the blackout upto 70 hours. In the view of long-term traffic trend, it took 5--6 weeks for recovery of the traffic volume there. On the other hand, in the backbone network, the rapid decrease (40--50%) in the traffic volume only lasted for a few hours due to the blackout near the epicenter, and the impact of the traffic decrease in the epicenter area on the backbone traffic is estimated to 15--25%. Furthermore, we confirmed the increases of the traffic generated by users who rushed to access to the network for obtaining up-to-date information and videostreams.