Protection and Restoration Schemes in Elastic Optical Networks

Abstract

Elastic optical networks (EON) are an emerging solution to improve the capacity and flexibility of optical transport networks. EONs are comprised of a flexgrid spectrum, bandwidth variable transponders (BVT), and supporting optical cross connections. The evolution of EONs has facilitated the grouping of optical signal carriers, or network media channels (NMC), into parent media channels (MC). Concatenating NMCs, which traverse the same source to destination, into a MC reduces the requirement for guard-bands between channels. This provides an opportunity to treat multiple channels as a single entity in routing algorithms, spectrum assignment, and survivability schemes. The literature review conducted in this thesis found that the research in the protection and restoration schemes utilizing NMC and MC entities is lacking. This thesis aims to provide different proposals for both protection and restoration that enhance the survivability, flexibility, and spectral efficiency of EONs. Through MC and NMC identifiers, protection or restoration schemes are employed with an associated Class of Service (CoS) to an individual NMC or a MC as a whole entity. The protection schemes proposed in this thesis are; selected, divided, and mixed protection. Selected protection aims to reduce the required reserved resources by only protecting high priority traffic within a MC. Divided protection offers flexibility by dividing protection resources in a MC to multiple protection paths. Mixed protection incorporates both selected and divided protection into one scheme. The protection schemes are analyzed against the pre-existing dedicated protection. Restoration schemes are also proposed in this thesis. The novel approach to restoration drops lower priority NMCs in the event of a link fault when there is insufficient spectrum to restore all NMCs within an MC. The proposed restoration scheme is compared to fundamental restoration techniques, that are available in the predecessor fixed grid networks. The proposed approaches in protection and restoration provide a solution to flexgrid survivability implementations and improve the efficiency of spectrum protected and restored in the event of a single link failure.