Benefits of Sub-band Virtual Concatenation for Enhancing Availability of Elastic Optical Networks

Sub-band virtual concatenation (VCAT) technique can help improve spectrum utilization of an elastic optical network (EON). On the other hand, availability is an important service level agreement (SLA) criterion for an optical transport network. This paper evaluates how the sub-band VCAT technique can enhance the availability of an EON. A quadratic programming optimization model and an efficient heuristic algorithm are developed to maximize availability-weighted network bandwidth. Also, an allowed maximal differential delay (MDD) between different sub-paths that make up a VCAT connection is considered as a constraint, and the related availability-weighted network bandwidth is evaluated. Considering the limited spectrum capacity of each transponder, we also extend the model to assign spectra based on each independent transponder. Simulation results show that the sub-band VCAT technique can significantly increase average network availability of an EON compared to the case without VCAT (non-VCAT). A trend is also observed that with an increasing MDD, the average network availability increases, but saturates for a large MDD. In addition, the limitation of the available transponders at each node can become a bottleneck for provisioning the bandwidth between node pairs.