Method for Determining Recovery Order for Successive Node Failures

Abstract

It is difficult to completely prevent failures of links and nodes in a communication network. Therefore, it is necessary to quickly recover the failed nodes. Since resources are generally limited at the time of a disaster, it is impossible to recover all failure nodes at the same time, and it must be recovered sequentially. However, as is often seen in recent large-scale earthquakes, the aftershocks often cause failures, give large damage again and again, and prevent the recovery. In such a situation, since a new failure may occur at any time during sequentially recovering many failures, the order of recovery significantly affects the communication quality of the network. Therefore, it is important to determine an appropriate recovery order so that the communication quality of a network keeps even in a situation that failures occur successively. In this paper, we propose a method of determining the node recovery order that as many nodes as possible keep to be connected even if successive node failures occur. First, we formulate this problem as an optimization problem, prove that the problem is NP-hard, and design a heuristic algorithm. We also evaluate the performance of the proposed algorithm by using the topology of various actual networks.