**7. Summary**

Since the Internet continues to grow globally and becomes ever more important in daily life, business, and research, the need for fault-tolerant service in network management becomes more urgent. However, during the network failures caused by the 2006 earthquake, it was shown that there are still many challenges in fault-tolerant network management research. Even though multiple fiber cores are installed together to provide backup service, they may be useless during severe natural disasters. Therefore, full-mesh or fiber-disjoint physical network topology should be designed for use during failures. On the available topology, it was seen that BGP routing provided backup AS paths, which was useful for the first step in restoration. However, the traffic engineering issues during restoration were difficult to solve because all the information, such as link capacity, available bandwidth, link delay, traffic load, and routing policy, had to be collected, interpreted, and acted on by human operators. In spite of BGP re-routing, we had to deal with a few single-link ASs to establish direct connections to the R&E networks. From this experience of network recovery during a significant natural disaster affecting several different countries and ISP's, we were able to gather valuable information on network management during emergencies. Therefore, in the Internet of the future, designers should focus on fault-tolerant network management study including robust physical topology, cross-layer restoration, traffic engineering combined with BGP routing, and simulation of failures in the network.

We would like to show the one example from this lesson. In August 2009, the earthquake happened again near Taiwan island and the fiber cut happened again. Table 1 tool was improved as "Compath" already and the table was constructed again for this disaster (Kurokawa, 2010). At that time, the medical demonstration was planned in Asian area and the connectivity of the Thailand was required. The compath table recommended that the TW should have become the hub for the southeast Asian area. This was against the policy of TEIN2, but the R&E networks object is to support the researchers and such the flexibility was approved and the tool from the lesson of the 2006 earthquake improved the network operations.
