Pre-configured Backup Protection with Limited Resource Sharing in Elastic Optical Networks

Abstract

In this paper, we address the problem of providing survivability in elastic optical networks (EONs). In EONs, unlike the traditional 50 GHz fixed grid, fine granular 12.5 GHz flexgrid is used and the frequency spectrum is used more efficiently. For providing survivability, we consider a recently proposed survivability approach known as pre-configured backup protection with sharing (PBPS) because of its benefits over traditional methods. In PBPS, backup paths can be pre-configured and at the same time they can share resources. Therefore, both short recovery time and efficient resource usage can be achieved. PBPS has earlier been investigated for fixed-grid and flexgrid (EONs) networks using switch architectures with the power splitting feature of variable optical splitters (VOSs) and combiners. A potential problem in PBPS is power loss due to possible repeated power splitting. To reduce the power loss, amplifiers can be used at additional high cost. Alternatively, an approach of limiting backup sharing has been investigated in fixed-grid networks. In this approach the number of power splitting on a backup lightpath at intermediate nodes is limited (to a threshold value) to reduce the total power loss. This approach limits the degree of backup sharing. PBPS with limited backup sharing has not been investigated for flexgrid networks (EONs) and this investigation is the focus of this paper. We carry out this investigation with detailed simulation experiments on different network topologies. Our findings are as follows. (1) As seen in fixed-grid networks, even with the small number of power splitting, significant blocking reduction is seen in EONs. (2) Unlike fixed-grid networks, the blocking performance of PBPS with the small number of power splitting is comparable to the performance associated to unlimited power splitting (unlimited sharing) and, therefore, PBPS with limited sharing is more effective in EONs when compared to fixed grid networks.