We analyzed how reliability will be improved by adopting inter-domain multi-path and multi-homing routing when the structure in the Internet changes. We identified the properties of the ideal network structure that will maximize the advantage of multi-path and multi-home routing using mathematical analyses. We focused on how each end-toend path is built, how many multi-paths exist and how each multi-path consists of multi-path and multi-homing segments. Second, we analyzed the trends in the recent changes in how the Internet is structured from the view point of interdomain multi-path routing. The mathematical analyses suggest that a large number of multi-paths or multi-homing is not necessary to effectively benefit from multi-path routing. However, it will be important to keep the path length short in the segments where multiple paths are not available. The analyses on the recent changes in the Internet structure suggest that multi-path routing will contribute to improvement of reliability in two different ways. For the autonomous systems away from the Internet core, multi-path routing will improve the reliability by going around the busy Internet core, while it will improve the reliability by distributing network traffic load through the Internet core for the autonomous systems close to the core.