Research On SBPP And Spectrum Defragmentation For Elastic Optical Networks

Traditional Wavelength Division Multiplexing(WDM) optical networks cannot keep up with the bandwidth requirement of the fast growth of Internet traffic due to its fixed grid granularity. On the other hand, elastic optical networks(EONs) are flexible in bandwidth allocation and efficient of spectrum utilization. Recently, EONs have received extensive interest. In this thesis, we focus on shared backup path protection(SBPP) and spectrum defragmentation techniques for distance adaptive EONs.Firstly, we consider distance adaptive dynamic routing and spectrum allocation(RSA) for EONs. For this, we develop a heuristic algorithm and an Integer Linear Programming(ILP) model. Simulation results show that compared to 1+1 protection and SBPP under the case of fixed route, our proposed algorithm can maximize spare capacity sharing among protection lightpaths. Secondly, we consider the protection lightpath-based hitless spectrum defragmentation scheme and employ SBPP technique to evaluate the benefit of the scheme. We propose two defragmentation triggering mechanisms, namely, batch defragmentation(BD) and defragmentation upon blocking(BTD). We also propose two defragmentation algorithms, namely, defragmentation with sequentially releasing and re-establishing protection lightpaths(SR-D) and defragmentation with jointly releasing and re-establishing protection lightpaths(JR-D). The network performances are evaluated from perspectives of bandwidth blocking probability(BBP) and average number of reconfigurations per successfully established lightpath service(ANR). Simulation results show that our proposed scheme is efficient to significaly reduce BBP, which however trades off with a larger ANR.