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Survivable traffic grooming in elastic optical networks — Shared path protection

This study investigates the survivable traffic grooming problem for elastic optical networks with flexible grid employing new transmission technologies, e.g., orthogonal frequency-division multiplexing (OFDM). In such networks, the strict ITU-T wavelength grid is not followed. Instead, optical transponders are developed to be capable of properly tuning their rates. Equipping the network with gridless and elastic optical paths allows us to efficiently use the optical spectrum. In this paper, we propose a novel elastic shared path protection (ESPP), which does not only provide the traditional backup sharing of shared path protection (SPP) (i.e., the backup capacity of one optical path (i.e., lightpath) can be shared among multiple backup paths, provided that their corresponding working paths are link-disjoint), but also explores a new opportunity of sharing enabled by the tunability of the transponders: in fact, the backup spectrum can be shared between two adjacent lightpaths on a link, if their corresponding working paths are link-disjoint. The elasticity of the transponder enables the expansion and contraction of the lightpaths, so that at one time, the backup spectrum is used by only one of the adjacent lightpaths. Note that in traditional wavelength-division-multiplexing (WDM) networks, the lightpaths are fixed-grid, rigid-bandwidth, nor can they overlap each other. Our results show that ESPP is more spectrum efficient than traditional SPP.