Provisioning, Recovery, and In-Operation Planning in Elastic Optical Networks

8 Spectrum Defragmentation

Alberto Castro¹, Lluís Gifre², Marc Ruiz² and Luis Velasco²

¹ University California Davis, Davis, CA, USA

² Universitat Politècnica de Catalunya, Barcelona, Spain

Dynamic operation of Elastic Optical Networks (EONs) might cause the optical spectrum to be divided into fragments, which makes it difficult to find the contiguous spectrum of the required width along the paths for incoming connection requests, thus leading to an increased blocking probability. To alleviate to some extent that spectrum fragmentation, we propose applying spectrum defragmentation, triggered before an incoming connection is blocked, to change the spectrum allocation of already established optical connections so as to make room for the new connection. Two different defragmentation schemes are presented: (i) spectrum reallocation and (ii) spectrum shifting. Spectrum reallocation changes the central frequency of already established connections without rerouting them. Because spectrum reallocation might cause traffic disruption, spectrum shifting can be applied as a hitless spectrum defragmentation procedure, so as to shift the central frequency of already established connections to create wider contiguous spectrum fragments for incoming connections. After studying the two spectrum defragmentation schemes (Integer Linear Programming (ILP) formulations and heuristic algorithms are proposed), we explore how the Application‐based Network Operations (ABNO) architecture can deal ...