Efficient Routing Method for Reducing Significant Outages in Optical Networks

Optical communication networks are operated with great care to avoid outages. In particular, significant outages that have a devastating impact on society must be avoided, and several countries specify “significance standards” for network outages. Although the impact of possible outages strongly depends on routing methods for requested connections, there has been no existing work that directly deals with these standards. This paper for the first time introduces a routing problem to minimize the outage impact on a given significance standard. The problem is shown to be NP-hard, and an efficient heuristic method is proposed. This method searches for a good solution by considering the problem as a shortest-path search, where the significance of a link failure is regarded as the link weight. Numerical experiments showed that the proposed method reduces significant outages by 30–40% compared with the conventional shortest-path method and 10-20% compared with the most-reliable-path method.