Fragmentation-aware algorithms for multipath routing and spectrum assignment in elastic optical networks

•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.