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Highlights • SDM-EON is novel technology to transmit high capacity data through optical networks. • Bandwidth blocking is improved if fragmentation is exactly controlled and measured. • Fragmentation problem is solved by using multipath mechanism per cores. • By introducing new fragmentation measurement, fragmentation in spectra can be controlled. • Three novel algorithms are introduced to resolve fragmentation problem in EON-SDM. Abstract An innovative technology to expand transmission capacity of optical backbone networks and to add flexibility to conventional WDM networks is Elastic Optical Networks with Space Division Multiplexing (EON-SDM). In EON-SDM, connection requests can be established in a much efficient manner than WDM networks and even EON network without SDM capability. The notion of increasing fiber capacity with Space Division Multiplexing (SDM) is almost as old as fiber communications itself. One of the important problems in EON-SDM is fragmentation created by dynamically establishing and releasing lightpaths over time, thus increasing connection blocking probability. In this article, three novel algorithms are introduced to resolve fragmentation problem and improve blocking probability in EON-SDM; called Fragmentation Measure Metric Aware with Routing and Spectrum and Core Assignment (FMMA-RSCA), Most Fragmented Path per Core (MFPC), and Spectrum Block Multipathing per Core (SBMC). These algorithms can reduce blocking probability by controlling fragmentation in cores since they try different ways in order to assign spectrum for a given connection request. By providing this opportunity in spectrum allocation and assignment, connection blocking probability is improved as proved based on our performance evaluation results. [ABSTRACT FROM AUTHOR]

• Fragmentation in EON is created by dynamically establishing and releasing lightpaths over time. • Six new algorithms are introduced to resolve the fragmentation problem. • Bandwidth is allocated for new connection in two stages. • A proper path is chosen based on our fragmentation metric in the second stage with multipath mechanism. • By filling small frequency slot gaps with subconnections, the chance of allocation of connections increases. • These algorithms can improve bandwidth utilization and blocking probability by controlling fragmentation. An innovative technology to expand transmission capacity of optical backbone networks is Elastic Optical Network (EON). EON adds flexibility to conventional WDM networks. In EON, the requested bandwidth could be allocated in a much efficient manner than in WDM networks. One of the important problems in EON is fragmentation created by dynamically establishing and tearing down lightpaths over the time, thus increasing connection blocking probability. In this article, six new algorithms are introduced to resolve the fragmentation problem and improve blocking probability; called Pure Multipath spectrum allocation in Two Stages (PM2S), multipath with considering PRE-assignment External Fragmentation Metric in two stages (PRE-EFM), multipath with considering POST assignment External Fragmentation Metric in two stages (POST-EFM), Fragmentation Measure Metric Aware with Routing and Spectrum Assignment (FMMA-RSA), Fragmentation Measure Metric Aware with Pre-Assignment (FMMA-PRE), and Fragmentation Measure Metric Aware with POST-assignment (FMMA-POST). Our main goal in these algorithms is reducing Blocking Probability (BP) by controlling fragmentation in each path since they try different ways in order to assign spectrum for a given connection request. Here, a connection demand is divided into multiple sizes to be setup in multiple routes. By providing this opportunity in spectrum allocation and assignment, connection blocking probability is improved as our performance evaluation results prove. [ABSTRACT FROM AUTHOR]