We investigate adaptive reconfiguration of sub-lambda and wavelength paths to deal with unpredictable traffic demands. To accommodate traffic effectively, wavelength paths need to be reconfigured cooperatively with sub-lambda paths while minimizing the number of migration sequences. Therefore, we propose a scheme for sub-lambda and wavelength path reconfiguration based on wavelength resource management in multi-layer transport networks. Three steps comprise the proposed scheme: wavelength resource management, reconfiguration trigger, and reconfiguration. First, management of the number of wavelength paths that can be accommodated between all node pairs is calculated for each path accommodated. Second, if that number is less than the threshold value set in advance for some node pair, reconfiguration is performed. Third, the sub-lambda and wavelength paths are reconfigured. In this scheme, we also propose a sub-lambda path reconfiguration algorithm that reconfigures multi-hop sub-lambda paths to single-hop paths first, and two wavelength path reconfiguration algorithms that reduce wavelength fragmentation and the number of migration sequences considering the accommodation rate. Numerical evaluation shows that the number of fibers is suppressed by 12%–14% and that the equipment cost is reduced by approximately 8%–9% compared to when no reconfiguration is used. The results also show that the number of migration sequences for the wavelength defragmentation algorithms is reduced by approximately 23%–35% compared to that for the conventional algorithm.
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