Lightpath fragmentation for efficient spectrum utilization in dynamic elastic optical networks

Abstract

Abstract-The spectrum-sliced elastic optical path network (SLICE) architecture has been presented as an efficient solution for flexible bandwidth allocation in optical networks. An homologous problem to the classical Routing and Wavelength Assignment (RWA) arises in such an architecture, called Routing and Spectrum Assignment (RSA). Imposed by current transmission technologies enabling the elastic optical network concept, the spectrum contiguity constraint must be ensured in the RSA problem, meaning that the bandwidth requested by any connection must be allocated over a contiguous portion of the spectrum along the path between source and destination nodes. In a dynamic network scenario, where incoming connections are established and disconnected in a quite random fashion, spectral resources tend to be highly fragmented, preventing the allocation of large contiguous spectrum portions for high datarate connection requests. As a result, high data-rate connections experience unfairly increased bocking probability in contrast to low data-rate ones. In view of this, the present article proposes a lightpath fragmentation mechanism that makes use of the idle transponders in the source node of a high data-rate connection request to fragment it into multiple low data-rate ones, more easily allocable in the network. Besides, aiming to support such an operation, a light-weight RSA algorithm is also proposed so as to properly allocate the generated lightpath fragments over the spectrum. Benefits of the proposed approach are quantified through extensive simulations, showing drastically reduced high data-rate connection blocking probability compared to a usual contiguous bandwidth allocation, while keeping the performance of low data-rate requests to similar levels.

Defragmentation in W-S-W Elastic Optical Networks

“…Several methods used to defragment FSUs may be distinguished: re-optimization [13], make-before-break [14], push-and-pull [15], and hop-tuning [16]. All of them are commonly used for defragmentation of an available spectrum used in links between EON nodes.…”

Single-path provisioning with multi-path recovery in flexgrid optical networks

“…Applied to WSON, authors in [6], [7] propose a mechanism for multiple lightpaths provisioning which satisfies extremely high bandwidth requirements whilst minimizes the amount of traffic affected by single link failures upper-bounding also differential delay. Authors in [8] propose using multi-path provisioning for flexgrid optical networks as a mechanism to increase network performance. The application of multi-path to recovery was introduced by authors in [9] where K disjoint paths are both provisioned and protected using SPP.…”

Routing, Spectrum, and Transponder Assignment in Elastic Optical Networks

“…Several previous works in [12], [35]- [38] considered the application of slice-ability in a dynamic traffic scenario. In these studies, when a lightpath request cannot be allocated as a single super-channel, slice-ability is used to split the request in a number of sub-lightpaths that are independently routed in the network and each one has to fit the ITU-T flexgrid.…”