Elastic optical networks (EONs) are considered a very promising solution for next-generation optical networks. Elastic spectral bandwidth allocation promotes spectrum utilization efficiency and thus increases the network capacity. One of the fundamental problems in EONs is the routing and spectrum allocation (RSA) problem. Since real EONs may provide only a few regular line rates, we comprehensively study in this paper the dynamic RSA problem in EONs with several mixed line rates. To solve the dynamic RSA problem efficiently, we decompose the problem into RSA subproblems. For the routing subproblem, we propose an efficient multiconstrained routing algorithm named sorted feasible paths searching (SFPS) to find the shortest feasible paths for dynamic traffic demands. The completeness, optimality, and complexity of SFPS are proved. For the spectrum allocation subproblem, we propose two spectrum allocation strategies named fixed segmentation and adaptive segmentation to assign spectrum for the noncommensurate traffic demands of EONs with mixed line rates. Simulation results prove that the proposed dynamic RSA algorithms are time efficient and perform better than existing dynamic RSA algorithms in terms of bandwidth blocking probability and spectrum fragmentation ratio in EONs with mixed line rates.

IP Fast Reroute (IP FRR) is the IETF standard for providing fast reaction to failures in IP and MPLS/LDP networks. In the past decade, several IP FRR proposals have been proposed, and among them Loop-Free Alternates (LFA) is the simplest, but it cannot achieve 100% single failure coverage. In contrast, Maximally Redundant Trees (MRT) can provide 100% single failure coverage and seems a promising scheme. However, MRT has some drawbacks as it can lead to long backup detours and heavy network congestion. In this paper we combine MRT with LFA to merge their advantages and improve the quality of protection. Observations of performance evaluation suggest that with almost same time and resource consumption as MRT, our mechanism can greatly enhance the quality of protection in terms of backup path length and maximum link utilization.

No abstract