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Received Jan 8, 2018; Revised Feb 27, 2018; Accepted Mar 5, 2018
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1. Introduction
Current and emerging communication and computing networks are expected to provide high reliability by achieving near-instantaneous restoration in the event that one or more network elements fail. This requires that network restoration plans be put in place such that in the event of failures, the network can immediately adjust, regroup, and/or revert to an alternative arrangement, usually in terms of a reroute, to continue and complete the given communication task [1]. Hence, developing network restoration models to cater for sudden failures, thereby improving the efficiency and reliability of our telecommunications and computing networks, is an imperative. Network (or routing) restoration (or recovery) is the field that describes the design and implementation of appropriate mechanisms and/or models for achieving desirable network reliability by creating proper backup plans for networks in the event of preconceived or unexpected failures [2].
The main goal of network restoration is to seek to instantaneously make available new routes once one or more network elements (e.g., links or nodes) fail, thereby avoiding disruption to network traffic. The new routes are usually either computed immediately at the point of failure or are usually preplanned even before such failure occurs. Generally, in research works that involve developing appropriate network restoration mechanisms for protection against failures, several factors have to be put into consideration. The most important factors are the cost of network infrastructure, length of rerouting paths, amount of the total capacity that has to be reserved for restoration or recovery from failure, and the time taken to achieve such network restoration. The design goal is always to achieve optimal productivity for the network with as much less resource and cost as possible over the shortest amount of time. Network restoration models are built around this goal. The restoration capacity problem, for instance, is designed to place the minimum amount of spare capacity needed in the network to restore a part of lost connections [3]. Several works have been carried out and more works are still being done in addressing...